JP2013099072A - Power supply device and led driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-isolated type power supply device and an LED driving device with which regardless of which one of both ends of a load circuit is ground-faulted, it is possible to reduce power supply to the load circuit without using a complicated construction.SOLUTION: A non-isolated type power supply device A1, which converts input power from a direct current power supply E1, whose negative electrode is grounded to a ground line G1, into desired direct current power and supplies the direct current power to a load circuit Y1, includes: a capacitor C1 electrically connected between one end of the load circuit Y1 and the negative electrode of the direct current power supply E1; and a capacitor C2 electrically connected between the other end of the load circuit Y1 and a positive electrode of the direct current power supply E1.

Description

  The present invention relates to a power supply device and an LED driving device.

  Conventionally, there is a power supply device that supplies DC power to a DC load, and is used in various fields (see, for example, Patent Document 1).

  For example, in the lighting field, LED (Light Emitting Diode) elements are actively used and their uses are diversified. In vehicle lighting, white LED elements are used in the passenger compartment, and are also used for headlights, daytime running lamps, and the like due to higher brightness.

  LED elements have a longer life and faster response than incandescent bulbs, and can be mounted compactly in structure. Moreover, various colors can be easily realized, and lighting control by dimming is easy. And lighting fixtures, such as a lamp, can be reduced in thickness, and since it can be mounted in three dimensions, there is an advantage that a free design that does not limit the shape such as a car design is possible.

  The luminaire described above includes an LED element and a power supply device that lights the LED element. By supplying a constant current to a light source formed by connecting a plurality of LED elements in series, the plurality of LED elements are Something that lights up with uniform brightness is provided.

  The power supply device uses a step-up chopper circuit when the output voltage (for example, the voltage across the LED elements connected in series) is higher than the input voltage, and uses a step-down chopper circuit when the output voltage is lower than the input voltage. Is done. A step-up / step-down chopper circuit is used when operating in both the step-up and step-down modes depending on the power supply environment and the load state.

  As an example of a conventionally used step-up / down chopper circuit, a configuration of a CUK circuit is shown in FIG.

  This CUK circuit is a non-insulated power supply device, and supplies DC power to an LED unit X101 in which a plurality of LED elements are connected in series, using a DC power supply E101 as an input power supply. The DC power supply E101 has its negative electrode grounded to the ground line G101.

  A series circuit of an inductor L101 and a switching element S101 is connected between the positive electrode and the negative electrode of the DC power supply E101. A series circuit of a capacitor C101 and a diode D101 is connected between both ends of the switching element S101, and a series circuit of an inductor L102 and a capacitor C102 is connected between both ends of the diode D101. The LED unit X101 is connected between both ends of the capacitor C102, and a direct current is supplied to the LED unit X101.

  In such a configuration, a series circuit in which the inductor L101, the capacitor C101, the inductor L102, and the LED unit X101 are sequentially connected is provided in the path from the positive electrode to the negative electrode of the DC power supply E101. The path between the negative electrode of the DC power supply E101 and one end of the LED unit X101 (the anode side of the LED element) is configured by a common line W101, and one end of the LED unit X101 has the same potential (or the ground line G101) (or Approximately the same potential). Further, the diode D101 has an anode connected to a connection point between the capacitor C101 and the inductor L102, and a cathode connected to the common line W101.

  Then, the switching element S101 is turned on / off by a control circuit (not shown), whereby DC power is supplied to the LED unit X101, and each LED element of the LED unit X101 is lit.

JP 2005-224049 A

  In FIG. 13, when the LED unit X101 is grounded (when the LED unit X101 is in contact with the ground line G101), the following occurs.

  First, when the other end side electric circuit Wa101 has a ground fault, a ground fault current is generated in a closed circuit passing through the positive electrode of the DC power source E101-inductor L101-capacitor C101-inductor L102-electric circuit Wa101-ground line G101-negative electrode of the DC power source E101. Flowing. However, the capacitor C101 separates the power supply side (DC power supply E101) and the load side (LED unit X101) in a DC manner, and the ground fault current is limited by the capacitor C101. Since both ends of the LED unit X101 are substantially short-circuited by the ground line G101, the LED unit X101 does not light up. The user can recognize that an abnormality has occurred by turning off the LED unit X101.

  On the other hand, when one end side electric circuit Wb101 is grounded, the electric circuit Wb101 is a part of the common line W101, and therefore the LED unit X101 continues to be lit. In the case of an in-vehicle lighting device, it can be considered that the operation of a vehicle is safe for the vehicle to operate even if an abnormality occurs. However, since the user cannot recognize that there is an abnormality, a problem may arise if the power supply device is continuously used in an abnormal state.

  For example, even if a wiring harness connecting the output of the power supply device and the LED unit X101 is sandwiched between some structures and the electric circuit Wb101 is in contact with the ground line G101 and causes a ground fault, an abnormality cannot be detected. become. If it is continuously used in a mode that is not in a normal state, problems such as overheating of the harness will occur. Further, there is a possibility that interference with a ground line of a nearby electrical component may occur.

  Therefore, a method of detecting a ground fault by connecting a detection resistor or the like to the common line W101 has been proposed, but there are problems such as detection accuracy and complicated control, and the configuration of the ground fault detection means is complicated. This was an increase in the number of parts and increased costs.

  The present invention has been made in view of the above reasons, and its purpose is to reduce the power supply to the load circuit without complicating the configuration even if either of both ends of the load circuit is grounded. An object is to provide an insulated power supply device and an LED driving device.

  The power supply apparatus of the present invention is a non-insulated power supply apparatus that converts input power from a DC power supply with one pole grounded into desired DC power and supplies it to a load circuit, and includes one end of the load circuit and the A first capacitor electrically connected between the one pole of the DC power supply and a second capacitor electrically connected between the other end of the load circuit and the other pole of the DC power supply; It is characterized by providing.

  In the present invention, a switching element that is electrically connected to the first and second capacitors and switches between charging and discharging of the first and second capacitors is provided, and the direct current is generated by turning on and off the switching element. It is preferable to include a boosting unit that boosts the voltage of the power supply, and a step-down unit that steps down the boosted voltage by the boosting unit when the switching element is turned on and off and applies the stepped-down voltage to the load circuit.

  In the present invention, the first inductor, the second capacitor, the second inductor, the load circuit, and the first capacitor are sequentially arranged on the path from the other pole of the DC power source to the one pole. A connected series circuit is provided, and the switching element is connected between a connection point between the first inductor and the second capacitor and the one pole of the DC power supply, Preferably, a diode is connected between a connection point between the capacitor and the second inductor and a connection point between the load circuit and the first capacitor.

  In the present invention, a switching element, the second capacitor, the first inductor, the load circuit, and the first capacitor are sequentially connected to a path from the other pole to the one pole of the DC power supply. A series circuit is provided, and a second inductor is connected between a connection point of the switching element and the second capacitor and the one pole of the DC power supply, and the second capacitor A diode is preferably connected between a connection point with the first inductor and a connection point between the load circuit and the first capacitor.

  In this invention, the first inductor, the second capacitor, the diode, the load circuit, and the first capacitor are connected in order to the path from the other pole of the DC power source to the one pole. A series circuit is provided, and a switching element is connected between a connection point between the first inductor and the second capacitor and the one pole of the DC power supply, and the second capacitor and the Preferably, a second inductor is connected between a connection point with the diode and a connection point between the load circuit and the first capacitor.

  In the present invention, the load circuit preferably includes a load composed of an LED element, an incandescent lamp, or a resistance element.

  In this invention, the load circuit preferably includes a third capacitor connected in parallel to the load.

  In the present invention, the load circuit includes a third inductor connected to one end of the load, a fourth inductor connected to the other end of the load, and a series of the load and the third and fourth inductors. And a third capacitor connected in parallel to the circuit.

  In the present invention, it is preferable that a resistor is connected in parallel to the first capacitor.

  In this invention, it is preferable to provide a plurality of the load circuits.

  An LED drive device according to the present invention is a non-insulated LED drive device that converts input power from a DC power source with one pole grounded into desired DC power and supplies the DC power to a load circuit composed of one or more LED elements. A first capacitor electrically connected between one end of the load circuit and the one pole of the DC power supply, and between the other end of the load circuit and the other pole of the DC power supply. And a second capacitor electrically connected to the capacitor.

  As described above, according to the present invention, in the non-insulated power supply device and the LED driving device, even if any of both ends of the load circuit is grounded, power is supplied to the load circuit without complicating the configuration. There is an effect that can be reduced.

1 is a block diagram illustrating an outline of a system according to a first embodiment. (A)-(c) It is a circuit diagram which shows the structural example of a load circuit same as the above. 6 is a circuit diagram showing a system configuration of Embodiment 2. FIG. It is a circuit diagram which shows another structure of a load circuit same as the above. It is a circuit diagram which shows another structure around the 1st capacitor | condenser same as the above. It is a circuit diagram which shows another system configuration same as the above. FIG. 6 is a circuit diagram illustrating a system configuration of a third embodiment. It is a circuit diagram which shows another structure of a load circuit same as the above. It is a circuit diagram which shows another system configuration same as the above. FIG. 6 is a circuit diagram illustrating a system configuration of a fourth embodiment. It is a circuit diagram which shows another structure of a load circuit same as the above. It is a circuit diagram which shows another system configuration same as the above. It is a circuit diagram which shows the conventional system configuration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a schematic configuration of a power supply device A1 according to the present embodiment. The power supply device A1 includes a converter unit A11 including capacitors C1 and C2 to form a non-insulated power supply device. As input power, DC power is supplied to the load circuit Y1.

  The DC power supply E1 has its negative electrode grounded to the ground line G1, and a capacitor C1 (first capacitor) is connected in series between the negative electrode of the DC power supply E1 and one end of the load circuit Y1, and the DC power supply E1 A capacitor C2 (second capacitor) is connected in series between the positive electrode and the other end of the load circuit Y1.

  One end of the load circuit Y1 is connected to the capacitor C1 through the electric circuit W11, and the other end of the load circuit Y1 is connected to the capacitor C2 through the electric circuit W12. That is, the electric circuits W11 and W12 at both ends of the load circuit Y1 are electrically connected to both electrodes of the DC power supply E1 through the capacitors C1 and C2, respectively. The electric circuit W11 is connected to the ground line G1 through the capacitor C1. Connected to.

  Thus, the electric circuit W12 includes the load circuit Y1 and the capacitor C1 between the electric circuit W12 and the ground line G1, and the electric circuit W11 includes the capacitor C1 between the electric circuit W11 and the ground line G1. Therefore, both electric circuits W11 and W12 that are both-end electric circuits of the load circuit Y1 have different potentials from the ground line G1.

  Converter unit A11 supplies DC power to load circuit Y1 through capacitors C1 and C2 and electric circuits W11 and W12 using DC power supply E1 as an input power supply.

  When the electric circuit W12 has a ground fault (in contact with the ground line G1), the power supply device A1 having such a configuration is closed through the positive electrode of the DC power supply E1, the capacitor C2, the electric circuit W12, the ground line G1, and the negative electrode of the DC power supply E1. A ground fault current flows in the circuit. Therefore, since it is different from the current path during normal circuit operation, power supply to the load circuit Y1 is suppressed, and the user can recognize that an abnormality has occurred in the power supply device A1 due to the operation stop of the load circuit Y1. .

  Further, when the electric circuit W11 is grounded (in contact with the ground line G1), the power supply device A1 has a positive electrode of the DC power supply E1, a capacitor C2, an electric circuit W12, a load circuit Y1, an electric circuit W11, a ground line G1, and a negative electrode of the DC power supply E1. A ground fault current flows in a closed circuit passing through. Therefore, since the current path is different from that during normal circuit operation, power supply to the load circuit Y1 is suppressed, and the user can confirm that an abnormality has occurred in the power supply device A1 due to the operation stop of the load circuit Y1. Can be recognized.

  Further, even if any of the electric circuits W11 and W12 is grounded, the power source side (DC power supply E1) and the load side (load circuit Y1) are separated in a DC manner by the capacitor C2, and the circuit is protected. .

  When the electric circuit W12 is grounded, a closed circuit is formed that passes through the ground line G1-electric circuit W12-load circuit Y1-electric circuit W11-capacitor C1-ground line G1. Moreover, when the electric circuit W11 has a ground fault, a closed circuit passing through the ground line G1-electric circuit W11-capacitor C1-ground line G11 is formed. That is, regardless of which of the electric circuits W11 and W12 is grounded, the one end side and the other end side of the capacitor C1 are substantially separated to protect the circuit.

  Thus, when the electric circuits W11 and W12 are grounded, the main circuit of the power supply device A1 is in the above-described state, so that it is not necessary to provide a control means for detecting and determining the ground fault, and the circuit configuration is simplified. Cost can be reduced. That is, regardless of which of the electric circuits W11 and W12 is grounded, the capacitors C1 and C2 of the converter unit A11 are used as grounding countermeasure capacitors, thereby supplying power to the load circuit Y1 without complicating the configuration. Can be reduced.

  The capacitor C2 is a capacitor that is used to perform the normal power supply operation of the converter unit A11, and this capacitor C2 is also used for the purpose of separating the power supply side and the load side in the event of a ground fault. . Therefore, it is sufficient to add only the capacitor C1 as a circuit component for ground fault countermeasures.

  FIGS. 2A to 2C are configuration examples of the load circuit Y1. One to a plurality of LED elements (FIG. 2A), a filament light bulb (FIG. 2B), and a resistive load (FIG. c)) and the like. When a filament light bulb is used for the load circuit Y1, a converter that makes the applied voltage constant is used. Since the LED element and the filament bulb are light source loads, they are turned off (or reduced) when a ground fault occurs in the electric paths W11 and W12, and the user can recognize that an abnormality has occurred in the power supply device A1. Even when a driving load such as a resistance load is used for the load circuit Y1, it can be recognized that an abnormality has occurred in the power supply device A1 due to the operation of the load circuit Y1 being stopped when a ground fault occurs in the electric circuits W11 and W12.

(Embodiment 2)
FIG. 3 shows a specific circuit configuration of the power supply device A1, which is a buck-boost chopper circuit having a CUK circuit as a basic configuration. Hereinafter, the reference numeral A1a is given to the power supply device of FIG. The same reference numerals are given to the same components as those in the first embodiment.

  The power supply device A1a having the CUK circuit as a basic configuration is a non-insulated power supply device, and uses a DC power supply E1 as an input power supply, and an LED drive device that supplies DC power to an LED unit X1 in which a plurality of LED elements are connected in series. Configure. The DC power supply E1 has its negative electrode grounded to the ground line G1.

  The inductor L1 (first inductor), capacitor C2 (second capacitor), inductor L2 (second inductor), load circuit Y1, capacitor C1 (first) is connected to the path from the positive electrode to the negative electrode of the DC power supply E1. 1 is connected in series. Switching element S1 is connected between the connection point of inductor L1 and capacitor C2 and the negative electrode of DC power supply E1. Furthermore, the anode of the diode D1 is connected to the connection point between the capacitor C2 and the inductor L2, and the cathode of the diode D1 is connected to the connection point between the load circuit Y1 and the capacitor C1.

  The load circuit Y1 is composed of a parallel circuit of an LED unit X1 in which a plurality of LED elements are connected in series and a capacitor C3 (third capacitor), and a power supply device is connected to the parallel circuit of the LED unit X1 and the capacitor C3. A direct current is supplied from A1a. The LED element of the LED unit X1 has an anode connected to the electric circuit W11 and a cathode connected to the electric circuit W12.

  Such a power supply device A1a includes a converter unit A11 (boost unit) having a boost function using a DC power source E1 as a power source and a converter unit A12 (step-down unit) having a step-down function using capacitors C1 and C2 as power sources. . The converter unit A11 includes an inductor L1, a switching element S1, capacitors C1 and C2, and a diode D1. The converter unit A12 includes a switching element S1, capacitors C1 and C2, a diode D1, and an inductor L2.

  Then, when the switching element S1 is turned on / off by a control circuit (not shown), DC power is supplied to the load circuit Y1, and each LED element of the LED unit X1 is lit.

  The operation of this circuit will be described below.

  First, as the operation of the converter unit A11 having a boosting function, when the switching element S1 is turned on, a current flows through the closed circuit of the DC power supply E1-inductor L1-switching element S1-DC power supply E1, and the inductor L1 stores magnetic energy. To do. When the switching element S1 is turned off, the magnetic energy of the inductor L1 is released by the closed circuit of the inductor L1-capacitor C2-diode D1-capacitor C1-DC power supply E1-inductor L1, and charges are accumulated in the capacitors C1 and C2. The By the on / off operation of the switching element S1, the voltage across the capacitors C1, C2 is boosted to a voltage higher than that of the DC power supply E1.

  Next, as the operation of the converter unit A12 having a step-down function, when the switching element S1 is turned on, the voltage across the capacitors C1 and C2 accumulated in the above operation becomes a power source, and the accumulated charges in the capacitors C1 and C2 are released. . Specifically, the accumulated charge of the capacitors C1 and C2 is released in a closed circuit of the capacitor C2-switching element S1-capacitor C1-load circuit Y1 (LED unit X1, capacitor C3) -inductor L2-capacitor C2. At this time, magnetic energy is stored in the inductor L2.

  When the switching element S1 is turned off, a counter electromotive force is generated in the inductor L2, and the inductor L2-diode D1-load circuit Y1 (LED unit X1, capacitor C3) is maintained so as to maintain the current direction when the switching element S1 is on. )-A current flows in the closed circuit of the inductor L2. By the on / off operation of the switching element S1, a voltage lower than the voltage across the capacitors C1 and C2 is applied to the load circuit Y1. Whether the voltage applied to the load circuit Y1 is higher or lower than the voltage of the DC power supply E1 can be set according to the operation (on duty, frequency) of the switching element S1 and circuit constants.

  As described above, the switching element S1 is turned on / off, so that the DC power supply E1 operates in the boost mode, and the voltages across the capacitors C1 and C2 operate in the step-down mode. The currents of the inductors L1 and L2 have a current waveform like a triangular wave, but the current of the LED unit X1 is a direct current smoothed by the capacitor C3.

  In the power supply device A1a based on the CUK circuit, one end of the capacitor C1 has the same potential (or substantially the same potential) as the ground line G1. Further, the capacitor C1 and the load circuit Y1 are connected by an electric circuit W11, and the load circuit Y1 and the inductor L2 are connected by an electric circuit W12. In FIG. 3, the electric circuit W <b> 11 is configured by electric circuits between the capacitor C <b> 1 and the LED unit X <b> 1 and between the capacitor C <b> 1 and the capacitor C <b> 3. Moreover, the electric circuit W12 is comprised by each electric circuit between LED unit X1-inductor L2, and between capacitor | condenser C3-inductor L2.

  Thus, the electric circuit W11 includes the capacitor C1 between the ground line G1, and the electric circuit W12 includes the load circuit Y1 and the capacitor C1 between the ground line G1. Therefore, both electric circuits W11 and W12 that are both-end electric circuits of the load circuit Y1 have different potentials from the ground line G1.

  The power supply device A1a based on such a CUK circuit has an inductor L1, a capacitor C2, and an inductor L2 from the positive electrode of the DC power supply E1, regardless of which of the electric circuits W11 and W12 is grounded (in contact with the ground line G1). A ground fault current flows in a closed circuit passing through. At this time, not only the capacitor C2 in the closed circuit is charged, but also the capacitor C1 is charged by the current supplied from the electric circuit W11. Therefore, even if any of the electric circuits W11 and W12 is grounded, the power supply side (DC power supply E1) and the load side (load circuit Y1) are separated in DC by the capacitors C1 and C2, and the circuit is protected. Is done.

  Note that the capacitor C2 is a capacitor used for performing a normal power supply operation of the CUK circuit, and this capacitor C2 is also used for the purpose of separating the power supply side and the load side in the event of a ground fault. Therefore, it is sufficient to add only the capacitor C1 as a capacitor for ground fault countermeasures.

  For example, the LED unit X1 may be disposed at a location away from the power supply device A1a, and a wiring harness that connects the output of the power supply device A1a and the LED unit X1 may be sandwiched between some structures. In this case, the electric circuits W11 and W12 may come into contact with the ground line G1, and a ground fault may occur.

  When the electric circuit W12 is grounded, a ground fault current flows in a closed circuit passing through the positive electrode-inductor L1-capacitor C2-inductor L2-electric circuit W12-ground line G1-negative electrode of the DC power supply E1. Since this is different from the current path during normal circuit operation, power supply to the load circuit Y1 is suppressed. The user can recognize that an abnormality has occurred in the power supply device A1a by turning off (or dimming) the LED unit X1.

  When the electric circuit W11 is grounded, the positive electrode of the DC power supply E1, the inductor L1, the capacitor C2, the inductor L2, the electric circuit W12, the load circuit Y1 (LED unit X1, the capacitor C3), the electric circuit W11, the ground line G1, and the DC power supply E1. A ground fault current flows in a closed circuit that passes through the negative electrode. Since this is different from the current path during normal circuit operation, power supply to the load circuit Y1 is suppressed. The user can recognize that an abnormality has occurred in the power supply device A1a by turning off (or dimming) the LED unit X1.

  Even if either of the electric circuits W11 and W12 is grounded, the ground fault current passes through the inductors L1 and L2, so that the steep ground fault current does not flow and the ground fault current has a gentle waveform to the circuit component. The stress is reduced. Then, the on / off drive of the switching element S1 may be stopped by detecting the extinction (or dimming) of the LED unit X1.

  FIG. 4 shows another form of the load circuit Y1. In the converter unit A12, the current supplied to the load circuit Y1 is divided into continuous, discontinuous, and critical modes depending on the value of the inductor L2, but the ripple value of the current flowing through the LED unit X1 varies greatly depending on the current waveform. Therefore, in FIG. 4, inductors L31 and L32 (third and fourth inductors) are connected in series to both ends of the LED unit X1, respectively, and a capacitor C3 (third capacitor) is connected in parallel to this series circuit. It has a filter function to reduce ripple current. The ripple current is determined by the value of the capacitor C3, the inductors L31 and L32, and the current mode.

  Further, as shown in FIG. 5, a resistor R1 may be connected in series with a capacitor C1. In this case as well, when the electric circuits W11 and W12 are grounded, the same operations and effects as described above can be obtained.

  FIG. 6 shows a power supply device A1b provided with a plurality of load circuits Y1, and an inductor L2 is connected in series to each of the load circuits Y1. In this case, the LED unit X1 of one or more load circuits Y1 is extinguished (or dimmed) and an abnormality has occurred in the power supply device A1b due to a ground fault in the connection circuit of any load circuit Y1. Can be recognized.

(Embodiment 3)
FIG. 7 shows a specific circuit configuration of the power supply device A1, and is a step-up / step-down chopper circuit having a ZETA SEPIC (Zeta Sepic) circuit as a basic configuration. Hereinafter, the reference numeral A1c is given to the power supply device of FIG. The same reference numerals are given to the same components as those in the first embodiment.

  The power supply device A1c having the ZETA SEPIC circuit as a basic configuration is a non-insulated power supply device, and uses LED power supply E1 as an input power supply to drive DC power to the LED unit X11 in which a plurality of LED elements are connected in series. Configure the device. The DC power supply E1 has its negative electrode grounded to the ground line G1.

  A switching element S11, a capacitor C2 (second capacitor), an inductor L11 (first inductor), a load circuit Y1, and a capacitor C1 (first capacitor) are provided on the path from the positive electrode to the negative electrode of the DC power supply E1. A series circuit connected in order is arranged. An inductor L12 (second inductor) is connected between the connection point between the switching element S11 and the capacitor C2 and the negative electrode of the DC power supply E1. Furthermore, the anode of the diode D11 is connected to the connection point between the load circuit Y1 and the capacitor C1, and the cathode of the diode D11 is connected to the connection point between the capacitor C2 and the inductor L11.

  The load circuit Y1 is configured by a parallel circuit of an LED unit X11 in which a plurality of LED elements are connected in series and a capacitor C13 (third capacitor). A power supply device is connected to the parallel circuit of the LED unit X11 and the capacitor C13. A direct current is supplied from A1c. The LED element of the LED unit X11 has an anode connected to the electric circuit W12 and a cathode connected to the electric circuit W11.

  Then, when the switching element S11 is turned on / off by a control circuit (not shown), DC power is supplied to the load circuit Y1, and each LED element of the LED unit X11 is lit. Note that the operation of the ZETA SEPIC circuit is well known and will not be described.

  In the power supply device A1c based on this ZETA SEPIC circuit, one end of the capacitor C1 has the same potential (or substantially the same potential) as the ground line G1. Further, the capacitor C1 and the load circuit Y1 are connected by an electric circuit W11, and the load circuit Y1 and the inductor L11 are connected by an electric circuit W12. In FIG. 7, the electric circuit W <b> 11 is configured by electric circuits between the capacitor C <b> 1 and the LED unit X <b> 11 and between the capacitor C <b> 1 and the capacitor C <b> 13. Further, the electric circuit W12 is configured by electric circuits between the LED unit X11 and the inductor L11 and between the capacitor C13 and the inductor L11.

  Thus, the electric circuit W11 includes the capacitor C1 between the ground line G1, and the electric circuit W12 includes the load circuit Y1 and the capacitor C1 between the ground line G1. Therefore, both electric circuits W11 and W12 that are both-end electric circuits of the load circuit Y1 have different potentials from the ground line G1.

  The power supply device A1c based on such a ZETA SEPIC circuit has a switching element S11, a capacitor C2, and a capacitor C2, from the positive electrode of the DC power supply E1, regardless of which of the electric circuits W11, W12 is grounded (in contact with the ground line G1). A ground fault current flows in a closed circuit passing through the inductor L11. At this time, not only the capacitor C2 in the closed circuit but also the capacitor C1 is charged by the current supplied from the electric circuit W11. Therefore, even if any of the electric circuits W11 and W12 is grounded, the power supply side (DC power supply E1) and the load side (load circuit Y1) are separated in DC by the capacitors C1 and C2, and the circuit is protected. Is done.

  The capacitor C2 is a capacitor that is used to perform a normal power supply operation of the ZETA SEPIC circuit, and this capacitor C2 is also used for the purpose of separating the power supply side and the load side at the time of a ground fault. . Therefore, it is sufficient to add only the capacitor C1 as a capacitor for ground fault countermeasures.

  For example, the LED unit X11 may be disposed at a location away from the power supply device A1c, and a wiring harness that connects the output of the power supply device A1c and the LED unit X11 may be sandwiched between some structures. In this case, the electric circuits W11 and W12 may come into contact with the ground line G1, and a ground fault may occur.

  And when the electric circuit W12 has a ground fault, a ground fault current flows in a closed circuit passing through the positive electrode-switching element S11 of the DC power supply E1, the capacitor C2, the inductor L11, the electric circuit W12, the ground line G1, and the negative electrode of the DC power supply E1. Since this is different from the current path during normal circuit operation, power supply to the load circuit Y1 is suppressed. The user can recognize that an abnormality has occurred in the power supply device A1c by turning off (or dimming) the LED unit X11.

  When the electric circuit W11 is grounded, the positive electrode of the DC power supply E1, the switching element S11, the capacitor C2, the inductor L11, the electric circuit W12, the load circuit Y1 (LED unit X11, the capacitor C13), the electric circuit W11, the ground line G1, and the DC power supply. A ground fault current flows in a closed circuit passing through the negative electrode of E1. Since this is different from the current path during normal circuit operation, power supply to the load circuit Y1 is suppressed. The user can recognize that an abnormality has occurred in the power supply device A1c by turning off (or dimming) the LED unit X11.

  Even if either of the electric circuits W11 and W12 has a ground fault, since the ground fault current passes through the inductor L11, a steep ground fault current does not flow, and the ground fault current has a gentle waveform, causing stress to the circuit components. Is reduced. Then, the on / off drive of the switching element S11 may be stopped by detecting the extinction (or dimming) of the LED unit X11.

  FIG. 8 shows another form of the load circuit Y1. In the power supply circuit A1c, the current supplied to the load circuit Y1 is divided into continuous, discontinuous, and critical modes depending on the value of the inductor L11. The ripple value of the current flowing through the LED unit X11 varies greatly depending on the current waveform. Therefore, in FIG. 8, inductors L41 and L42 (third and fourth inductors) are respectively connected in series to both ends of the LED unit X11, and a capacitor C13 (third capacitor) is connected in parallel to this series circuit. It has a filter function to reduce ripple current. The ripple current is determined by the value of the capacitor C13, the inductors L41 and L42, and the current mode.

  Further, as shown in FIG. 5, a resistor R1 may be connected in series with a capacitor C1. In this case as well, when the electric circuits W11 and W12 are grounded, the same operations and effects as described above can be obtained.

  FIG. 9 shows a power supply device A1d provided with a plurality of load circuits Y1, and an inductor L11 is connected in series to each of the load circuits Y1. In this case, the LED unit X11 of one or more load circuits Y1 is extinguished (or dimmed) due to the ground fault of the connection circuit of any load circuit Y1, and an abnormality has occurred in the power supply device A1d. Can be recognized.

(Embodiment 4)
FIG. 10 shows a specific circuit configuration of the power supply device A1, and is a step-up / step-down chopper circuit having a SEPIC (sepic) circuit as a basic configuration. Hereinafter, the reference numeral A1e is given to the power supply device of FIG. The same reference numerals are given to the same components as those in the first embodiment.

  The power supply device A1e having the SEPIC circuit as a basic configuration is a non-insulated power supply device, and uses a DC power supply E1 as an input power supply, and an LED drive device that supplies DC power to an LED unit X21 in which a plurality of LED elements are connected in series. Configure. The DC power supply E1 has its negative electrode grounded to the ground line G1.

  The inductor L21 (first inductor), the capacitor C2 (second capacitor), the diode D21, the load circuit Y1, and the capacitor C1 (first capacitor) are sequentially provided on the path from the positive electrode to the negative electrode of the DC power supply E1. A connected series circuit is arranged. A switching element S21 is connected between the connection point of the inductor L21 and the capacitor C2 and the negative electrode of the DC power supply E1. Further, an inductor L22 (second inductor) is connected between a connection point between the capacitor C2 and the diode D21 and a connection point between the load circuit Y1 and the capacitor C1. The diode D21 has an anode connected to the capacitor C2 and a cathode connected to the load circuit Y1.

  The load circuit Y1 is configured by a parallel circuit of an LED unit X21 in which a plurality of LED elements are connected in series and a capacitor C23 (third capacitor). A power supply device is connected to the parallel circuit of the LED unit X21 and the capacitor C23. A direct current is supplied from A1e.

  Then, when the switching element S21 is turned on / off by a control circuit (not shown), DC power is supplied to the load circuit Y1, and each LED element of the LED unit X21 is lit. Note that the operation of the SEPIC circuit is well known and will not be described.

  In the power supply device A1e having the SEPIC circuit as a basic configuration, one end of the capacitor C1 has the same potential (or substantially the same potential) as the ground line G1. Further, the capacitor C1 and the load circuit Y1 are connected by an electric circuit W11, and the load circuit Y1 and the diode D21 are connected by an electric circuit W12. In FIG. 10, the electric circuit W <b> 11 is configured by electric circuits between the capacitor C <b> 1 and the LED unit X <b> 21 and between the capacitor C <b> 1 and the capacitor C <b> 23. Moreover, the electric circuit W12 is comprised by each electric circuit between LED unit X21 and the diode D21, and between the capacitor | condenser C23 and the diode D21.

  Thus, the electric circuit W11 includes the capacitor C1 between the ground line G1, and the electric circuit W12 includes the load circuit Y1 and the capacitor C1 between the ground line G1. Therefore, both electric circuits W11 and W12 that are both-end electric circuits of the load circuit Y1 have different potentials from the ground line G1.

  The power supply device A1e having such a SEPIC circuit as a basic configuration has an inductor L21, a capacitor C2, and a diode D21 from the positive electrode of the DC power supply E1 regardless of which of the electric circuits W11 and W12 is grounded (in contact with the ground line G1). A ground fault current flows in a closed circuit passing through. At this time, not only the capacitor C2 in the closed circuit but also the capacitor C1 is charged by the current supplied from the electric circuit W11. Therefore, even if any of the electric circuits W11 and W12 is grounded, the power supply side (DC power supply E1) and the load side (load circuit Y1) are separated in DC by the capacitors C1 and C2, and the circuit is protected. Is done.

  Note that the capacitor C2 is a capacitor used for performing a normal power supply operation of the SEPIC circuit, and this capacitor C2 is also used for the purpose of separating the power supply side and the load side during a ground fault. Therefore, it is sufficient to add only the capacitor C1 as a capacitor for ground fault countermeasures.

  For example, the LED unit X21 may be disposed at a location away from the power supply device A1e, and a wiring harness that connects the output of the power supply device A1e and the LED unit X21 may be sandwiched between some structures. In this case, the electric circuits W11 and W12 may come into contact with the ground line G1, and a ground fault may occur.

  When the electric circuit W12 is grounded, a ground fault current flows in a closed circuit passing through the positive electrode-inductor L21 of the DC power supply E1, the capacitor C2, the diode D21, the electric circuit W12, the ground line G1, and the negative electrode of the DC power supply E1. Since this is different from the current path during normal circuit operation, power supply to the load circuit Y1 is suppressed. The user can recognize that an abnormality has occurred in the power supply device A1e by turning off (or dimming) the LED unit X21.

  When the electric circuit W11 is grounded, the positive electrode of the DC power supply E1, the inductor L21, the capacitor C2, the diode D21, the electric circuit W12, the load circuit Y1 (LED unit X21, the capacitor C23), the electric circuit W11, the ground line G1, and the DC power supply E1. A ground fault current flows in a closed circuit that passes through the negative electrode. Since this is different from the current path during normal circuit operation, power supply to the load circuit Y1 is suppressed. The user can recognize that an abnormality has occurred in the power supply device A1e by turning off (or dimming) the LED unit X21.

  Even if either of the electric circuits W11 and W12 has a ground fault, since the ground fault current passes through the inductor L21, a steep ground fault current does not flow, and the ground fault current has a gentle waveform, causing stress to the circuit components. Is reduced. Then, the on / off drive of the switching element S21 may be stopped by detecting the extinction (or dimming) of the LED unit X21.

  FIG. 11 shows another form of the load circuit Y1. In the power supply circuit A1e, the current supplied to the load circuit Y1 is divided into continuous, discontinuous, and critical modes depending on the value of the inductor L22. The ripple value of the current flowing through the LED unit X21 varies greatly depending on the current waveform. Therefore, in FIG. 11, inductors L51 and L52 (third and fourth inductors) are connected in series to both ends of the LED unit X21, respectively, and a capacitor C23 (third capacitor) is connected in parallel to this series circuit. It has a filter function to reduce ripple current. The ripple current is determined by the value of the capacitor C23, the inductors L51 and L52, and the current mode.

  Further, as shown in FIG. 5, a resistor R1 may be connected in series with a capacitor C1. In this case as well, when the electric circuits W11 and W12 are grounded, the same operations and effects as described above can be obtained.

  FIG. 12 shows a power supply device A1f provided with a plurality of load circuits Y1, and a diode D21 is connected in series to each of the load circuits Y1. In this case, the LED unit X21 of one or more load circuits Y1 is extinguished (or dimmed) and an abnormality has occurred in the power supply device A1d due to a ground fault in the connection circuit of any load circuit Y1. Can be recognized.

A1 power supply device A11 converter E1 DC power supply C1 capacitor (first capacitor)
C2 capacitor (second capacitor)
Y1 load circuit G1 ground line

Claims (11)

A non-insulated power supply device that converts input power from a DC power supply with one pole grounded into desired DC power and supplies the power to a load circuit,
A first capacitor electrically connected between one end of the load circuit and the one pole of the DC power supply, and electrically between the other end of the load circuit and the other pole of the DC power supply. A power supply device comprising: a connected second capacitor. A switching element that is electrically connected to the first and second capacitors and switches between charge and discharge of the first and second capacitors;
A boosting unit that boosts the voltage of the DC power supply by turning on and off the switching element;
The power supply device according to claim 1, further comprising: a step-down unit that steps down a step-up voltage by the step-up unit when the switching element is turned on and off and applies the step-down voltage to the load circuit. A series path in which a first inductor, the second capacitor, a second inductor, the load circuit, and the first capacitor are sequentially connected to the path from the other pole to the one pole of the DC power supply A circuit is provided,
The switching element is connected between a connection point between the first inductor and the second capacitor and the one pole of the DC power supply,
The diode is connected between the connection point of the second capacitor and the second inductor and the connection point of the load circuit and the first capacitor. Power supply. A series circuit in which a switching element, the second capacitor, the first inductor, the load circuit, and the first capacitor are sequentially connected to the path from the other pole of the DC power source to the one pole. Provided,
A second inductor is connected between a connection point between the switching element and the second capacitor and the one pole of the DC power supply,
2. The diode according to claim 1, wherein a diode is connected between a connection point between the second capacitor and the first inductor and a connection point between the load circuit and the first capacitor. Power supply. A path extending from the other pole of the DC power source to the one pole is provided with a series circuit in which a first inductor, the second capacitor, a diode, the load circuit, and the first capacitor are connected in order. And
A switching element is connected between a connection point between the first inductor and the second capacitor and the one pole of the DC power supply,
The second inductor is connected between a connection point between the second capacitor and the diode and a connection point between the load circuit and the first capacitor. Power supply.   The power supply apparatus according to claim 1, wherein the load circuit includes a load including an LED element, an incandescent lamp, or a resistance element.   The power supply apparatus according to claim 6, wherein the load circuit includes a third capacitor connected in parallel to the load.   The load circuit is connected in parallel to a series circuit of a third inductor connected to one end of the load, a fourth inductor connected to the other end of the load, and the load and the third and fourth inductors. The power supply device according to claim 6, further comprising a third capacitor.   The power supply apparatus according to claim 1, wherein a resistor is connected in parallel to the first capacitor.   The power supply apparatus according to claim 1, comprising a plurality of the load circuits. A non-insulated LED drive device that converts input power from a DC power supply with one pole grounded into desired DC power and supplies the converted DC power to a load circuit composed of one or more LED elements,
A first capacitor electrically connected between one end of the load circuit and the one pole of the DC power supply, and electrically between the other end of the load circuit and the other pole of the DC power supply. An LED driving device comprising: a connected second capacitor.

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