Power supply suitable for connection to a DC power supply system

Abstract

A power supply device capable of suppressing arc discharge at an interruption point in a DC power supply system. [Solution] The power supply device 10 has a DC-DC converter 12 and is equipped with a reverse connection fault prevention element 6 connected to either the positive or negative input terminal, and an arc discharge suppression circuit 8 inserted between the reverse connection fault prevention element 6 and the DC-DC converter 12. The reverse connection fault prevention element 6 is an element that restricts current from the input terminal to one direction by allowing current to flow from the positive input terminal and blocking current from the negative input terminal, and the arc discharge suppression circuit 8 has a capacitor element that is charged by current from the positive input terminal, maintaining the capacitor element in a charged state while current from the DC power supply system continues, and discharging the capacitor element when the current from the DC power supply system is interrupted, thereby gradualing the voltage drop at the positive input terminal and suppressing arc discharge at the interruption point.

Description

[Technical Field]

[0001] The present invention relates to a power supply device suitable for connection to a DC power supply system. [Background technology]

[0002] In recent years, the use of renewable energy such as solar power has been encouraged, and the number of power generation systems such as solar power generation systems installed in factories, offices, commercial stores, and ordinary homes has been increasing. Because the power generated by such power generation systems is usually DC power, there is a movement to supply the generated DC power to electrical appliances as DC, that is, to promote the conversion of indoor wiring to DC (the introduction of DC power supply systems) (for example, Patent Document 1).

[0003] DC power supply is an efficient method. This is because DC power generated by solar power generation can be supplied to home appliances and other devices via a general household power distribution line without being converted to AC power. Furthermore, the power sources for home appliances and other devices do not need to convert AC power to DC power. For example, in the residential DC voltage supply system shown in Figure 1 of Patent Document 1, DC power from solar cell 2 passes through a backflow prevention diode 3 and a noise filter 5, and then branches off as DC power, efficiently supplying it to the power supply units (DC-DC converters 8a, 8c, inverters 8e, 8g) of each home appliance 6. In this way, DC power supply can be said to be a system suitable for achieving carbon neutrality. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-283841 [Patent Document 2] Patent No. 5456575 [Patent Document 3] Patent No. 6471381 [Patent Document 4] Patent No. 6768244 [Patent Document 5] Patent No. 4121431 [Patent Document 6] Japanese Patent Application Laid-Open No. 2016-157364 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when using electrical appliances connected to such DC power supply systems, it is important to note that arc discharges are likely to occur and persist. For example, (1) when using an ON / OFF switch between the DC power supply system and an electrical appliance to turn on or off the supply of DC power to the electrical appliance, arc discharges may occur and persist between the terminals when the switch is turned from ON to OFF. Also, (2) if a short interruption occurs due to a poor connection in the supply line from the DC power supply system, arc discharges may occur and persist at the point of the poor connection. And (3) if a fuse connected to the supply line from the DC power supply system melts due to an overcurrent, arc discharges may occur and persist at the melted point. These arc discharges are particularly noticeable when the voltage is high. If no measures are taken to prevent arc discharges in such areas, secondary damage, such as damage to electronic components, may occur due to arc discharges. In this document, open / close switches, poor connections, blown fuses, etc. on the DC power supply line from the DC power supply system are collectively referred to as "DC current interruption points, or simply as interruption points."

[0006] Known countermeasures against arc discharges when interrupting direct current include switches and circuit breakers with an arc extinguishing function. For example, Figures 7 and 8 of Patent Document 2 show an arc extinguishing circuit 1 configured integrally with a compact toggle switch 30. The primary side of the compact toggle switch 30 is connected to a direct current power source DC, and the secondary side (load side) is connected to the arc extinguishing circuit 1 (a circuit in which a capacitor element 4 is connected in series to a parallel connection of a diode element 2 and a resistor element 3). When the compact toggle switch 30 opens, the capacitor element 4 of the arc extinguishing circuit 1 discharges, thereby suppressing the arc discharge.

[0007] 3 of Patent Document 3 shows a DC current switching device 1. In this switching device 1, an arc discharge suppression circuit (a series circuit of a diode element D1 and a capacitor element C) is connected in parallel to a switch SW1. When the switch SW1 is opened, a current from a DC power source E0 flows to the capacitor element C, charging the capacitor element C and suppressing arc discharge at the switch SW1.

[0008] Moreover, Figure 6 of Patent Document 4 shows a circuit configuration that uses the power of the DC power supply 1 to prevent arc discharge in the switch 4. When the switch 4 is opened, a voltage is generated in the secondary coil L2 of the transformer provided on the electric circuit upstream of the switch 4, and this voltage is applied to the electric circuit downstream of the switch 4, eliminating the potential difference across the switch 4 and suppressing arc discharge.

[0009] As shown in Patent Documents 2 to 4, various types of arc discharge suppression circuits have been developed for switches and circuit breakers for DC power supply systems. However, not all switches connected to DC power supply systems are necessarily equipped with sufficient arc discharge countermeasures. When conventional AC power supply systems in commercial facilities and factories are retrofitted to DC power supply systems, existing AC wall switches are prone to causing and sustaining arc discharge when interrupting DC current. Typically, existing switches are equipped with arc discharge countermeasures or replaced with DC switches equipped with arc discharge countermeasures, but there is a possibility that existing AC switches will be used as is in the DC power supply system.

[0010] The inventors have considered that in order to suppress arc discharge at the interruption point on the DC power supply system side, it is more advantageous to implement arc discharge countermeasures in the power supply device itself than to implement arc discharge countermeasures in the switches, etc. on the DC power supply system side. This is because, when the power supply device is connected to the DC power supply system, arc discharge at such a point can be suppressed regardless of whether arc discharge countermeasures are implemented in the switches, etc., upstream.

[0011] The inventors investigated conventional countermeasures against arc discharge in power supply devices and found that, for example, Figure 3 of Patent Document 5 shows a power supply circuit equipped with an arc discharge protection device 20. When an arc discharge occurs in this power supply circuit, an electrode plate 21 installed nearby absorbs the arc and generates a discharge signal due to the absorbed arc. Based on this discharge signal, a control unit 12 stops the operation of the drive unit, thereby extinguishing the arc discharge.

[0012] 1 of Patent Document 6 has a control function for extinguishing arc discharge when arc discharge occurs in the electric path between solar cell 200A and DC-DC converter 110A due to poor contact or the like. This power control device 100A has a DC-DC converter 110A, an arc detection unit 120A, and a control unit 140A, and when arc discharge occurs in the electric path, arc detection unit 120A detects the occurrence of an arc based on current information from the input unit, and control unit 140A extinguishes the arc discharge by controlling the step-up ratio of DC-DC converter 110A so that the input voltage to DC-DC converter 110A increases.

[0013] The conventional power supply devices shown in Patent Documents 5 and 6 have the arc discharge countermeasures of detecting the occurrence of an arc discharge and then initiating an operation to extinguish the arc discharge in accordance with the detection result, but the power supply devices themselves were not equipped with the function to suppress the occurrence of arc discharge itself.

[0014] An object of the present invention is to provide a power supply device that is suitable for connection to a DC power supply system, and in particular, that can suppress arc discharge at a point where DC current is interrupted. [Means for solving the problem]

[0015] That is, the power supply device of the present invention is a power supply device having a DC-DC converter that converts a DC voltage from a DC power supply system into a DC voltage for a load, positive and negative input terminals for connection to a DC power supply system; a reverse connection fault prevention element connected to the positive or negative input terminal; an arc discharge suppression circuit inserted between the reverse connection fault prevention element and the DC-DC converter, The reverse connection fault prevention element is an element that restricts the current from the input terminal to one direction by allowing a current to flow from the input terminal of a positive electrode and blocking a current from the input terminal of a negative electrode, The arc discharge suppression circuit has a capacitor element that is charged by current from the positive input terminal, and maintains the capacitor element in a charged state while current from the DC power supply system continues. When the current from the DC power supply system is interrupted, the capacitor element discharges, thereby gradualing the voltage drop at the positive input terminal and suppressing arc discharge at the interruption point.

[0016] wherein the arc discharge suppression circuit is a circuit in which a parallel circuit of a resistor element and a diode element is connected in series with the capacitor element; a cathode of the diode element is connected to a positive electrode of the DC-DC converter; an anode of the diode element is connected to one electrode of the capacitor element; The other electrode of the capacitor element is preferably connected to the negative electrode of the DC-DC converter.

[0017] Furthermore, a DC current supply capacitor element is inserted between the arc discharge suppression circuit and the DC-DC converter to maintain the supply of DC current during a driving period of the DC-DC converter, It is preferable that when current from the DC power supply system is interrupted, both the DC current supply capacitor element and the capacitor element of the arc discharge suppression circuit are discharged to suppress arc discharge at the interruption point.

[0018] Furthermore, a common mode / normal mode noise filter circuit is inserted between the input terminal and the reverse connection fault prevention element, It is preferable that when the current from the DC power supply system is interrupted, both the normal mode noise capacitor element of the common mode / normal mode noise filter circuit and the capacitor element of the arc discharge suppression circuit are discharged to suppress arc discharge at the interruption point.

[0019] Furthermore, it is preferable that a fuse element for interrupting an excessive current that may enter the positive input terminal is connected to the input terminal.

[0020] It is also preferable that the load is a light emitting element for illumination, and the DC-DC converter is a constant current converter that controls the current flowing through the light emitting element for illumination to be constant. [Effects of the Invention]

[0021] According to the above configuration, the power supply device of the present invention includes a reverse connection fault prevention device, an arc discharge suppression circuit, and a DC-DC converter, so that arc discharge at the DC current interruption point can be suppressed, making it suitable for connection to a DC power supply system. Connecting such a power supply device can improve the long-term reliability of DC power supply systems for home, commercial, and industrial use. These effects are due to the following functions. (1) Arc discharge suppression function: The power supply unit itself has a built-in arc discharge suppression circuit, so arc discharge at interruption points such as open / close switches on the DC power supply system can be suppressed regardless of whether or not arc discharge countermeasures are in place at such interruption points. (2) Reverse connection fault prevention function: By combining the arc discharge suppression circuit and reverse connection fault prevention element, if the polarity of the input terminal of the power supply device is connected in reverse to the DC power supply system (called "reverse connection"), the reverse connection fault prevention element prevents the reverse flow of DC current within the power supply device, preventing failure of not only the DC-DC converter but also the arc discharge suppression circuit. Furthermore, when the power supply device is connected correctly to the DC power supply system, the arc discharge suppression circuit and reverse connection fault prevention element do not interfere with each other's functions and each operates normally. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing a DC power supply system that supplies DC power to a plurality of power supply devices. [Figure 2] 1 is a diagram showing the overall configuration of a power supply device according to an embodiment of the present invention; [Figure 3] 10 is an example of a circuit diagram when the power supply device is applied to a power supply device for LED lighting. [Figure 4] FIG. 10 is a diagram showing the connection position of a reverse connection fault prevention element (diode element). [Figure 5] FIG. 1 is a diagram showing an example of a circuit configuration of a DC-DC converter. [Figure 6] Circuit diagram of the experimental device used for the contact separation test. [Figure 7] A list of contact disconnection test results (whether or not arc discharge occurred). [Figure 8] Waveform data showing the results of a contact disconnection test (whether or not arc discharge occurred). DETAILED DESCRIPTION OF THE INVENTION

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power supply device according to the present invention will now be described with reference to the accompanying drawings.

[0024] First, an example of the configuration of a DC power supply system 100 that supplies DC power to multiple power supply devices will be described using Figure 1. The main power source of the DC power supply system 100 is an AC / DC converter 102 connected to a commercial AC power source, and auxiliary power sources such as a solar power generator 105 and a wind power generator 106 can be connected to positive and negative DC power supply lines 103A, 103B from the AC / DC converter 102. In addition, a storage battery 107 as an emergency power source and a resistance midpoint earth circuit 108 as a safety circuit can also be connected. Such a DC power supply system 100 is installed in factories, offices, commercial stores, or ordinary homes.

[0025] The positive output terminals of both the solar power generator 105 and the wind power generator 106 are connected to the positive DC power feed line 103A via diodes D105 and D106. When the outputs of the generators 105 and 106 reach the voltage of the DC power feed line 103A, these renewable energies flow through the diodes D105 and D106 and are supplied to the DC power feed line 3A.

[0026] The positive output terminal of the storage battery 107 is connected to the anode of a diode D107, and the cathode of this diode D107 is connected to the DC power supply line 103A. In addition, a series connection consisting of a diode D117, a switch element SW117, and a resistor R117, which has the polarity opposite to that of diode D107, is connected in parallel to diode D107. Switch element SW117 turns on when the voltage of the storage battery 107 drops below a specified value (charging start voltage), and charging begins using the voltage on the DC power supply line 103A. Switch element SW117 also turns off when the voltage of the storage battery 107 reaches another specified value (charging stop voltage) through charging, and charging stops. These start and stop of charging operations are performed automatically.

[0027] The DC power supply system 100 includes a main power source (AC / DC converter 102), an auxiliary power source (photovoltaic generator 105 and wind power generator 106), and an emergency power source (storage battery 107), but may include only the main power source, only the auxiliary power source, a combination of the main power source and the auxiliary power source, a combination of the main power source and the emergency power source, or a combination of the auxiliary power source and the emergency power source.

[0028] A plurality of power supply devices 10 are connected in parallel to positive and negative DC power supply lines 103A, 103B of the DC power supply system 100, and DC power is supplied to a load 20 (for example, a home appliance, an LED for lighting, etc.) via the power supply devices 10. A switch SW10 for turning on / off the supply of DC power to the power supply devices 10 is inserted in the electric path between the positive DC power supply line 103A and the power supply devices 10. Because the DC power supply system 100 is connected to various DC power supply sources (such as a solar power generator 105, a wind power generator 106, and a storage battery 107), it is preferable to widen the rated voltage range of the power supply devices 10, for example, to 240 to 400 V, so that the power supply devices 10 can be driven by DC power from each supply source.

[0029] Fig. 2 is an overall configuration diagram of power supply device 10. Power supply device 10 is composed of surge circuit 2, filter circuit 4, reverse connection fault prevention element 6, arc discharge suppression circuit 8, and DC-DC converter 12, which uses a switching regulator including a switching element such as a MOSFET. Fig. 2 shows a case where power supply device 10 is formed separately from load 20 and installed at a distance from load 20, but power supply device 10 and load 20 may also be integrated.

[0030] The power supply device 10 of this embodiment may include a DC-DC converter (also called an LED driver) for general constant current control for lighting LEDs. The LED driver converts DC power from the DC power supply system 100 into DC power with a constant current value according to the lighting LED (light emitting element for lighting) which is the load 20, and realizes constant current control of the lighting LED.

[0031] Here, a specific description will be given using an example circuit configuration of the power supply device 10 shown in Fig. 3. Fig. 3 shows an example circuit configuration when the power supply device 10 is applied to a power supply device for LED lighting.

[0032] The power supply device 10 in Fig. 3 has three input terminals (positive, negative, and ground). The positive and negative input terminals are connected to positive and negative DC power supply lines 103A and 103B of an external DC power supply system 100. The ground input terminal is grounded.

[0033] The surge circuit 2 in Figure 3 is a protection circuit against lightning surges such as induced lightning. It includes, for example, two current fuses F1 and F2 installed on the positive line and a varistor element Z1 connecting the midpoint between these two current fuses F1 and F2 and the negative line. Varistor element Z1 is normally in the OFF (non-conducting) state, but when a voltage exceeding the varistor voltage (e.g., 560 V) is applied, it switches ON (conducting) and forms a bypass circuit for the surge. In other words, when varistor element Z1 receives a lightning surge, it bypasses the surge, protecting the power supply device 10. The rated interrupting current of the first-stage current fuse F1 is set high, so it will not easily melt even if a high current flows through varistor element Z1. However, if a current larger than expected flows or if varistor element Z1 maintains a short circuit, current fuse F1 will melt and ensure safety.

[0034] On the other hand, for abnormal current flowing toward the load side of varistor element Z1, the second-stage current fuse F2, which has a rated breaking current commensurate with the abnormal current, will function. In other words, if an abnormal current flows toward the load side of varistor element Z1, current fuse F2 will blow, ensuring a safer state.

[0035] In this way, when a lightning surge occurs, the first-stage current fuse F1 and varistor element Z1 control the excess current, and when an abnormal current flows inside, the second-stage current fuse F2 quickly cuts off the circuit, improving the safety of the circuit as a whole.

[0036] Note that a capacitor element, a resistor element, or a combination of these may be used as a surge absorbing element in place of the varistor element Z1 in the surge circuit 2. Also, the surge circuit 2 may have a simpler configuration (a configuration consisting of only a current fuse connected to the positive input terminal).

[0037] The filter circuit 4 in FIG. 3 is a common-mode / normal-mode noise filter, also known as a line filter, that removes noise components (common-mode noise and normal-mode noise) contained in the DC voltage from the positive and negative input terminals. In this embodiment, the filter circuit 4 includes, from the surge circuit 2 side, grounding capacitors CY1 and CY2, a normal-mode noise capacitor C1 provided on the primary side of the choke coil, a common-mode choke coil (for common-mode noise; the common-mode inductor component is represented by LF), and a normal-mode noise capacitor C2 provided on the secondary side of the choke coil. The grounding capacitors CY1 and CY2 connect the positive line to ground and the negative line to ground, respectively. Capacitors C1 and C2 connect the positive and negative lines. The capacitances and inductances of these capacitors vary depending on the power supply device. For example, in a power supply device of 160 W or less, the capacitance of the grounded capacitors CY1 and CY2 is set to several thousand pF, the capacitance of C1 and C2 is set to 0.04 to 2 μF, and the inductance of LF is set to several tens of mH or less.

[0038] The reverse connection fault prevention element 6 in FIG. 3 is a diode element D with its anode connected to the positive electrode of the filter circuit 4 and its cathode connected to the positive electrode of the arc discharge suppression circuit 8. However, the reverse connection fault prevention element 6 is not limited to the diode element D. The reverse connection fault prevention element 6 may be any element that allows current to flow from the positive input terminal and blocks current from the negative input terminal, thereby unidirectionally restricting the DC current from the DC power supply system 100 within the power supply device 10. By providing such a reverse connection fault prevention element 6, DC from the DC power supply system 100 does not flow in the reverse direction within the power supply device 10 even if the power supply device 10 is accidentally reverse-connected to the DC power supply system 100. In this embodiment, the withstand voltage of the diode element D may be, for example, 400 V or higher. The connection location of the diode element D is not limited to the positive electrode line as shown in FIG. 4A, but may also be the negative electrode line as shown in FIG. 4B. In other words, the diode element D may be connected to a line from either the positive or negative input terminal. In the case of FIG. 4(B), the anode of the diode element D is connected to the negative electrode side of the arc discharge suppression circuit 8, and the cathode is connected to the negative electrode side of the filter circuit 4.

[0039] Here, the reason for arranging the diode element D closer to the load than the surge circuit (varistor element Z1) will be explained. If the diode element D is arranged closer to the input side than the varistor element Z1 between the lines, when a lightning surge enters between the lines, the varistor element Z1 will enter a conductive state, causing an excessive current to flow, and there is a possibility that the diode element D will be damaged by this excessive current. On the other hand, by arranging the diode element D closer to the load than the varistor element Z1, as in this embodiment, the large current caused by the lightning surge will not flow through the diode element D, preventing damage to the diode element D.

[0040] Next, the arc discharge suppression circuit 8 of Fig. 3 is a circuit configured by connecting a resistor element R49 and a diode element D1 in parallel to a capacitor element C22 in series. Specifically, the cathode of the diode element D1 is connected to the positive electrode side of the input terminal, the anode of the diode element D1 is connected to one electrode of the capacitor element C22, and the other electrode of the capacitor element C22 is connected to the negative electrode side of the input terminal. When the switch SW10 of Fig. 1 is turned on and DC power is supplied to the power supply device 10, the DC current that has passed through the diode element D flows through the resistor element R49 of the arc discharge suppression circuit 8 to the capacitor element C22. The DC current accumulates (charges) the capacitor element C22. Then, the capacitor element C22 remains charged while the DC current from the DC power supply system 100 continues to flow. However, immediately after the DC current is interrupted from the DC power supply system 100, the capacitor element C22 releases (discharges) charge via the diode element D1, which causes a gradual drop in the voltage at the positive input terminal. As a result, the potential difference at the point where the DC current is interrupted in the DC power supply system 100 (for example, the switch SW10) does not increase suddenly (the potential difference remains zero for a very short time), and the occurrence of arc discharge at the interrupted point is suppressed.

[0041] Any of electrolytic capacitors, film capacitors, and ceramic capacitors can be used for the capacitor element C22. Of these, film capacitors are most suitable because they have a wide capacitance range and a longer lifespan than electrolytic capacitors. Ceramic capacitors are expensive in terms of capacity within the voltage range of this embodiment, but they can be used. Electrolytic capacitors have a relatively short lifespan, and arc discharge cannot be suppressed once their lifespan expires and capacitance loss occurs. Therefore, electrolytic capacitors can be used as long as they are used within a specified usage period.

[0042] A temperature variable resistor TH1 for inrush current protection may be provided on the positive electrode line between the arc discharge suppression circuit 8 and the constant current converter 12. That is, when an inrush current flows into the power supply device 10 upon switching on the switch SW10, the resistance of the temperature variable resistor TH1 increases as its own temperature rises, thereby suppressing the inrush current to the DC-DC converter 12 and protecting it.

[0043] The specific circuit configuration of the DC-DC converter 12 (constant current converter) in Figure 3 is not particularly limited. A general step-down converter such as that shown in Figure 5(A) or a flyback converter such as that shown in Figure 5(B) can be used. A capacitor C4 connecting the positive and negative lines is inserted between the temperature variable resistor TH1 and the DC-DC converter 12. This capacitor C4 is a DC current supply capacitor that maintains the supply of DC current while the DC-DC converter 12 is operating.

[0044] In this embodiment, the DC current supply capacitor C4 is inserted closer to the DC-DC converter 12 than the arc discharge suppression circuit 8, so that when current is interrupted in the DC power supply system 100, both the DC current supply capacitor C4 and the capacitor element C22 of the arc discharge suppression circuit 8 discharge, and they cooperate to suppress arc discharge at the interruption point. In this case, the charge in the DC current supply capacitor C4 is consumed first, followed by the charge in the capacitor element C22 of the arc discharge suppression circuit 8.

[0045] Furthermore, in this embodiment, the common-mode / normal-mode noise filter circuit 4 is inserted upstream of the arc discharge suppression circuit 8, so that the arc discharge suppression function is exerted by the multiple capacitor elements (C4, C22, C1, and C2), including the normal-mode noise capacitors C1 and C2 of the filter circuit 4. In other words, when current in the DC power supply system is interrupted, the four capacitor elements - the DC current supply capacitor C4, the capacitor element C22 of the arc discharge suppression circuit 8, and the normal-mode noise capacitors C1 and C2 - discharge and cooperate to suppress arc discharge at the interruption point. In this case, the charge of the DC current supply capacitor C4 is consumed first, followed by the charge of the capacitor element C22 of the arc discharge suppression circuit 8, and finally the charge of the normal-mode noise capacitors C1 and C2.

[0046] As described above, the power supply device 10 of this embodiment includes the reverse connection fault prevention device 6, the arc discharge suppression circuit 8, and the DC-DC converter 12, making it possible to suppress arc discharge and providing a power supply device 10 suitable for connection to a DC power supply system 100. In particular, the power supply device 10 can improve the long-term reliability of DC power supply systems 100 for home, commercial, and industrial use. These effects are based on the following functions.

[0047] Arc discharge suppression function: The power supply device 10 itself has a built-in arc discharge suppression circuit 8, which suppresses arc discharge at DC current interruption points, such as the switch SW10 of the DC power supply system 100, regardless of whether or not arc discharge countermeasures are in place at such points. As a result, for example, when upgrading an existing AC power supply system to a DC power supply system, arc discharge can be suppressed even if the existing AC switch SW is reused, which results in reduced renovation costs.

[0048] Reverse connection fault prevention function: By combining the arc discharge suppression circuit 8 with the reverse connection fault prevention element 6 (diode element D), even if the power supply device 10 is reverse-connected to the DC power supply system 100, the arc discharge suppression circuit 8 prevents a reverse flow of DC current in the power supply device 10, preventing failures not only in the DC-DC converter 12 but also in the arc discharge suppression circuit 8. Furthermore, when the power supply device 10 is properly connected to the DC power supply system 100, the arc discharge suppression circuit 8 and the reverse connection fault prevention element 6 (diode element D) operate normally without interfering with each other's functions.

[0049] Although the power supply device 10 of this embodiment has been described as having a function of suppressing arc discharge at the switch SW10, the present invention is not limited to this. For example, the power supply device 10 can similarly exhibit a function of suppressing arc discharge at a poor connection on a DC power supply line or at a fuse installation location in a DC power supply system.

[0050] Furthermore, since the power supply device 10 of this embodiment is provided with the arc discharge suppression circuit 8, it is possible to normally complete the blowing of the current fuse elements F1 and F2 even if no arc discharge countermeasures are taken against the current fuse elements F1 and F2 themselves in the surge circuit 2. In contrast, if the arc discharge suppression circuit 8 is not provided, when the current fuse elements F1 and F2 blow, an arc discharge may occur and continue at the blown location, which could result in abnormal blowing.

[0051] Furthermore, since the power supply device 10 itself has the arc discharge suppression circuit 8 built in, even when the power supply device 10 is removed from the DC power supply system 100 and attached to another DC power supply system, the arc discharge suppression function is still exhibited, contributing to the long-term reliability of the DC power supply system to which it is attached.

[0052] To demonstrate the effectiveness of the power supply device of the present invention, a contact disconnection test was conducted using an experimental device. Figure 6 shows the circuit configuration of the experimental device used in the test. E0 is a DC power supply, SW is a variable speed disconnection switch, 8 is an arc discharge suppression circuit, and R0 is a resistive load. The experimental device was configured so that the variable speed disconnection switch SW was connected to the positive line of the DC power supply E0, the arc discharge suppression circuit 8 was connected downstream of that, and the resistive load R0 was connected to the arc discharge suppression circuit 8.

[0053] The test conditions were as follows: The disconnection speed of the switch SW was set to three different values ​​(2.5, 5, and 10 mm / sec). Under the same disconnection speed conditions, the power consumption of the resistive load R0 was set to nine different values ​​(10, 20, 40, 60, 80, 100, 120, 140, and 160 W) ranging from 10 to 160 W. In addition, the capacitance of the capacitor element C22 of the arc discharge suppression circuit 8 was set to six different values ​​(0.1, 0.22, 0.44, 0.68, 1, and 2 μF).

[0054] The current and voltage difference between the contacts were monitored and recorded when the switch SW (contacts) was released under the release speed conditions. Figures 8(A) and (B) are representative examples of the current waveform data and voltage difference waveform data when the contacts were released. One division on the horizontal axis represents 1 msec. Figure 8(A) shows the case where no arc discharge occurred; at the time the switch SW was released, the current waveform drops to zero, and the voltage difference waveform rises gradually from zero (compared to the drop in the current waveform), with no waveform disturbance. On the other hand, Figure 8(B) shows the case where an arc discharge occurred; immediately after the switch SW was released, both the current waveform and the voltage difference waveform become significantly disturbed, and this disturbance continues for a certain period of time.

[0055] In the contact disconnection test, the occurrence of arc discharge was determined based on the waveform data of the monitored current and voltage difference. The test results (presence or absence of arc discharge) are shown in the table in Figure 7. The table in Figure 7 shows the cells for each test condition. Cells under test conditions in which arc discharge occurred are shown in gray. Cells under test conditions in which no arc discharge occurred are shown in white.

[0056] The test results in Figure 7 show that when the separation speed condition was 10 mm / sec, arc discharge occurred under all power consumption conditions (10 to 160 W) when the capacitance of capacitor element C22 was 0.1 μF. When the capacitance of capacitor element C22 was increased to 0.22 μF, no arc discharge occurred under power consumption conditions of 10 to 100 W. With a capacitance of 0.44 μF or higher, no arc discharge occurred under any power consumption condition. Next, when the separation speed condition was reduced to 5 mm / sec, no arc discharge occurred for the 10 W and 60 W power consumption even when the capacitance of capacitor element C22 was 0.22 μF, but arc discharge occurred for other capacitances. For capacitances of 0.44 μF or higher, no arc discharge occurred for any resistive load. From the results of the above two separation speed conditions (5 mm / sec, 10 mm / sec), it is clear that the faster the separation speed condition, the easier it is to suppress arc discharge.

[0057] Furthermore, when the separation speed condition was lowered to 2.5 mm / sec, there was a power consumption condition under which arc discharge occurred for all capacitance conditions of 0.44 μF or higher. Arc discharge also occurred at power consumption of 60, 100, and 140 W under the 2 μF capacitance condition. Based on the results of this separation speed condition (2.5 mm / sec), the separation speed condition for obtaining the arc discharge suppression effect in the experimental equipment is 5 mm / sec or higher.

[0058] 7, the capacitance of capacitor element C22 of arc discharge suppression circuit 8 is preferably within the range of 0.22 to 100 μF when the separation speed is 5 mm / sec or faster. If the capacitance exceeds 100 μF, the capacitor element becomes too large, increasing the cost of the power supply device, increasing the area occupied by the capacitor element on the board, and increasing the size of the power supply device, and electrically increasing the inrush current. More preferably, the capacitance of capacitor element C22 of arc discharge suppression circuit 8 is within the range of 0.44 to 100 μF when the separation speed is 5 mm / sec or faster.

[0059] The power supply device of the present invention is particularly suitable as a power supply device for a load with a power consumption in the range of 10 to 1000W. [Explanation of symbols]

[0060] 2 Surge Circuit 4. Filter Circuit 6. Reverse connection fault prevention element 8 Arc Suppression Circuit 12 DC-DC converter 10 Power supply 20 Load 100 DC power supply system C1 Normal noise capacitor (filter circuit) C2 Normal noise capacitor (filter circuit) C4 DC current supply capacitor C22 Capacitor element (arc discharge suppression circuit) D Diode element (reverse connection fault prevention element) D1 Diode element (arc discharge suppression circuit) F1, F2 current fuse (surge circuit) R49 Resistor element (arc discharge suppression circuit) SW10 switch (breaker) Z1 Varistor element (surge circuit)

Claims

1. A power supply device having a DC-DC converter that converts a DC voltage from a DC power supply system into a DC voltage for a load, positive and negative input terminals for connection to a DC power supply system; a reverse connection fault prevention element connected to the positive or negative input terminal; an arc discharge suppression circuit inserted between the reverse connection fault prevention element and the DC-DC converter, The reverse connection fault prevention element is an element that restricts the current from the input terminal to one direction by allowing a current to flow from the input terminal of a positive electrode and blocking a current from the input terminal of a negative electrode, the arc discharge suppression circuit has a capacitor element that is charged by a current from the positive input terminal, the capacitor element is kept in a charged state while a current from the DC power supply system continues, and when the current from the DC power supply system is interrupted, the capacitor element discharges, thereby gradualing a voltage drop at the positive input terminal and suppressing arc discharge at the point of interruption.

2. the arc discharge suppression circuit is a circuit in which a parallel circuit of a resistor element and a diode element is connected in series with the capacitor element, a cathode of the diode element is connected to a positive electrode of the DC-DC converter; an anode of the diode element is connected to one electrode of the capacitor element; 2. The power supply device according to claim 1, wherein the other electrode of said capacitor element is connected to the negative electrode of said DC-DC converter.

3. Furthermore, a DC current supply capacitor element is inserted between the arc discharge suppression circuit and the DC-DC converter to maintain the supply of DC current during a driving period of the DC-DC converter, 2. The power supply device according to claim 1, wherein when a current interruption occurs in the DC power supply system, both the DC current supply capacitor element and the capacitor element of the arc discharge suppression circuit discharge to suppress arc discharge at the interruption point.

4. Furthermore, a common mode / normal mode noise filter circuit is inserted between the input terminal and the reverse connection fault prevention element, 2. The power supply device according to claim 1, wherein when a current interruption occurs on the DC power supply system side, both a normal mode noise capacitor element of the common mode / normal mode noise filter circuit and a capacitor element of the arc discharge suppression circuit discharge to suppress arc discharge at the interruption point.

5. 2. The power supply device according to claim 1, further comprising a fuse element connected to said positive input terminal for interrupting an excessive current that may flow in.

6. 6. The power supply device according to claim 1, wherein the load is a light-emitting element for lighting, and the DC-DC converter is a constant current converter that controls the current flowing through the light-emitting element for lighting to be constant.

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