Power unit

Abstract

To provide a power unit which can reduce noise.SOLUTION: A power unit 12 comprises a main circuit 20 and a grounding part 38. The main circuit 20 comprises: an input circuit 21 having a rectifier circuit 27 which rectifies input power to output power after rectification from the rectifier circuit 27 to a pair of output lines 30, 31; and a power conversion circuit 22 having a switching element Q1 connected with the output lines 30, 31 to convert power after the rectification. The grounding part 38 is placed closer to the power conversion circuit 22 than the input circuit 21 and connected closer to the input circuit 21 than a connection point P1 at which the switching element Q1 is connected to the output line 31 via capacitors C4, C5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a power supply device. [Background technology]

[0002] 2. Description of the Related Art Power supply devices are known that rectify input power, convert the rectified power into a predetermined power by a switching element of a power conversion circuit, and supply the power to a load.

[0003] In such a power supply device, in order to comply with the standards for radiated electric field strength set forth in the Electrical Appliance and Material Safety Law, it is desirable to reduce noise, preferably without adding any countermeasure components. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-21587 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a power supply device capable of reducing noise. [Means for solving the problem]

[0006] A power supply device according to an embodiment includes a main circuit and a grounding unit. The main circuit includes an input circuit having a rectifier circuit that rectifies input power and outputs the rectified power from the rectifier circuit to a pair of output lines, and a power conversion circuit connected to the output lines and having a switching element that converts the rectified power. The grounding unit is disposed closer to the power conversion circuit than the input circuit and is connected via a capacitor to the input circuit than a connection point at which the switching element is connected to the output line. Effect of the Invention

[0007] According to the power supply device of the embodiment, a reduction in noise can be expected. [Brief description of the drawings]

[0008] [Figure 1] 1 is a circuit diagram of a lighting device including a power supply device according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a substrate of the power supply device. [Diagram 3] FIG. 11 is a circuit diagram of a lighting device including a power supply device of a comparative example. [Figure 4] FIG. 4 is a schematic diagram of a substrate of a power supply device according to a comparative example. [Diagram 5] FIG. 11 is a schematic diagram of a substrate of a power supply device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The first embodiment will be described below with reference to FIGS.

[0010] 1 shows a lighting device 10. The lighting device 10 includes a light source 11, which is a load, and a power supply device 12 that receives AC power, which is input power, from an AC power supply E, which is an external power supply, and supplies lighting power, which is DC power, to the light source 11, which is load power.

[0011] A light emitting element such as a light emitting diode (LED) is used as the light source 11. The light emitting element may be a semiconductor light emitting element such as an organic electroluminescence (EL) element, other than a light emitting diode. The light source 11 may be integrally arranged in the fixture body of the lighting device 10, or may be arranged in a light source unit that is detachable from the fixture body, and may be electrically connected to the power supply device 12 when the light source unit is attached to the fixture body.

[0012] The power supply device 12 includes a main circuit 20, which is a power supply circuit for operating a load and a lighting circuit for lighting the light source 11. The main circuit 20 includes an input circuit 21 for inputting AC power from an AC power supply E, a power conversion circuit 22 for converting the power input from the input circuit 21 into lighting power and supplying it to the light source 11, and a control circuit 23 for controlling the power conversion circuit 22.

[0013] The input circuit 21 includes a filter circuit 26 for reducing noise, a rectifier circuit 27 for rectifying the AC voltage of the AC power into a DC voltage, and a smoothing capacitor C1 which is a smoothing circuit for smoothing the DC voltage that is the rectified power.

[0014] The filter circuit 26 includes a line filter, such as a capacitor connected between a pair of input lines 29 connected to both ends of the AC power source E, and a common mode choke coil, to reduce noise in a predetermined frequency band. Note that the input circuit 21 may include a fuse for preventing overcurrent, a varistor for lightning surge protection, and the like, in the stage preceding the filter circuit 26.

[0015] The rectifier circuit 27 is, for example, a full-wave rectifier of a diode bridge in which four rectifier elements are combined, and full-wave rectifies the AC voltage of the AC power from the AC power source E. The rectifier circuit 27 has a pair of input terminals connected to a pair of input lines 29, and a pair of output terminals connected to a pair of output lines (main lines) 30, 31, which are a pair of main lines of the main circuit 20.

[0016] One output line 30 is a high potential line (positive line), and the other output line 31 is a low potential line (negative line).

[0017] The smoothing capacitor C1 is connected between the pair of output lines 30, 31 so as to be connected in parallel between the pair of output terminals of the rectifier circuit 27, and smoothes the DC voltage rectified by the rectifier circuit 27.

[0018] The power conversion circuit 22 also includes a power factor correction circuit 34 and a constant current circuit 35 .

[0019] The power factor correction circuit 34 is composed of a boost chopper circuit that boosts the rectified (rectified and smoothed) DC voltage in order to improve the power factor. The power factor correction circuit 34 includes an inductor L1, a switching element (first switching element) Q1, a diode D1, and a capacitor C2, and a series circuit of the inductor L1 and the switching element Q1 is connected to both ends of the smoothing capacitor C1, and a series circuit of the diode D1 and the capacitor C2 is connected to both ends of the switching element Q1.

[0020] The switching element Q1 is, for example, a field effect transistor such as a MOS-FET, with its drain connected to the high potential side of the capacitor C1 via the inductor L1, its source connected to the low potential side of the capacitor C1, and its gate connected to the control circuit 23.

[0021] The constant current circuit 35 is configured with a step-down chopper circuit that steps down the DC voltage boosted by the power factor correction circuit 34 to a lighting voltage, which is a predetermined DC voltage at which the light source 11 lights up, and makes it a constant current. The constant current circuit 35 includes a switching element (second switching element) Q2, a diode D2, an inductor L2, and a capacitor C3, and a series circuit of the switching element Q2 and the diode D2 is connected to both ends of the capacitor C2, a series circuit of the inductor L2 and the capacitor C3 is connected to both ends of the diode D2, and the light source 11 is connected to both ends of the capacitor C3.

[0022] The switching element Q2 is, for example, a field effect transistor such as a MOS-FET, with its drain connected to the connection point between the cathode of the diode D1 and the capacitor C2, its source connected to the connection point between the cathode of the diode D2 and the inductor L2, and its gate connected to the control circuit 23.

[0023] The control circuit 23 is also connected to the gate of the switching element Q1 of the power factor correction circuit 34 and the gate of the switching element Q2 of the constant current circuit 35, and controls the on / off of each of the switching elements Q1 and Q2. Specifically, the control circuit 23 controls the switching operation of the switching elements Q1 and Q2 by PWM (Pulse Width Modulation).

[0024] The control circuit 23 performs feedback control (constant current control) on the switching operation of the switching element Q2 so that the current supplied to the light source 11 becomes a constant current of a target value based on the value of the current flowing through the light source 11. In the low-potential side output line 31, a resistor R1 serving as a current detection unit is provided between the low-potential side of the light source 11 and the low-potential side of the capacitor C3, and the value of the current flowing through the light source 11 (a current value proportional to the current of the light source 11) is detected from the connection point between this resistor R1 and the low-potential side of the light source 11.

[0025] The power supply device 12 also includes a grounding portion 38 that is grounded to the main body of the lighting device 10 via a power supply case that covers the power supply device 12 or the like.

[0026] The grounding portion 38 is disposed on the power conversion circuit 22 side of the input circuit 21 including the rectifier circuit 27 and the smoothing capacitor C1, and between the input circuit 21 and the power conversion circuit 22 (power factor correction circuit 34).

[0027] The ground part 38 is connected to a connection point P2, which is a ground connection point located closer to the input circuit 21 than a connection point P1, which is a switching element connection point to which the source of the switching element Q1 is connected, via capacitors C4 and C5 with respect to the low-potential output line 31. The connection point P2 of the ground part 38 is connected to a position on the input circuit 21 side of the output line 31 than the position of the ground part 38.

[0028] Next, FIG. 2 shows a schematic diagram of the board 40 of the power supply device 12. As shown in FIG.

[0029] The substrate 40 is formed in a long rectangular plate shape extending from the AC power input side to the lighting power output side. The substrate 40 is made of an insulating material such as glass epoxy as a base material, and has a single-phase or multi-layer wiring pattern formed on one or both sides.

[0030] An input connector 41 to which an AC power source E is connected is disposed on one end of the substrate 40 in the longitudinal direction, and an output connector 42 to which the light source 11 is connected is disposed on the other end.

[0031] Between the input connector 41 and the output connector 42 of the substrate 40, the input circuit 21, the power factor correction circuit 34 of the power conversion circuit 22, and the constant current circuit 35 are arranged.

[0032] A space region 43 is provided between the input circuit 21 and the power conversion circuit 22 of the substrate 40, and the ground portion 38 and the capacitors C4 and C5 are disposed in this space region 43.

[0033] The switching element Q1 of the power factor correction circuit 34 includes an element portion 44 having an insulating molded element body, and three terminals 45 protruding from the element portion 44. The three terminals 45 are inserted into the substrate 40 and soldered to the wiring pattern, and the terminal 45 connected to the source of the switching element Q1 is connected to the output line 31. The element portion 44 is disposed on the substrate 40 so as to extend from the position where the terminal 45 is connected to the substrate 40 toward the input circuit 21, on one end side of the substrate 40 in the longitudinal direction. At least a part of the element portion 44 is disposed in the space region 43.

[0034] A heat dissipation section 46, which is thermally connected to the switching element Q1, is electrically connected and disposed on the grounding section 38. The heat dissipation section 46 is made of a metal plate having heat dissipation and electrical conductivity, and is provided, for example, in an L-shape. One end side of the heat dissipation section 46 is disposed on the substrate 40, and fixed to the substrate 40 at the position of the grounding section 38 with, for example, two screws, and the screws located on the grounding section 38 are soldered to the grounding section 38, so that the heat dissipation section 46 is electrically connected to the grounding section 38 via the screws. An element section 44 of the switching element Q1 is disposed on the heat dissipation section 46, and a screw is screwed from the element section 44 to the substrate 40 through the heat dissipation section 46, so that the element section 44 and the heat dissipation section 46 are fixed integrally to the substrate 40, and the element section 44 and the heat dissipation section 46 are in contact with each other so as to be in pressure contact and are thermally connected.

[0035] The other end of the heat dissipation section 46 is positioned at a side position of the substrate 40, and with the substrate 40 placed in the power supply case of the power supply device 12, it is positioned along the side plate of the power supply case and fixed to the side plate of the power supply case with a screw, so that the heat dissipation section 46 and the power supply case are in pressure-welded contact and thermally connected, and are electrically conductive so that the ground section 38 is grounded to the power supply case.

[0036] As described above, on the substrate 40, the grounding part 38 is disposed closer to the power conversion circuit 22 than the input circuit 21 including the rectifier circuit 27 and the smoothing capacitor C1, and is disposed between the input circuit 21 and the power conversion circuit 22. In addition, the grounding part 38 is connected to the low-potential output line 31 via the capacitors C4 and C5 to a connection point P2 that is closer to the input circuit 21 than a connection point P1 to which the source of the switching element Q1 is connected. The connection point P2 of the grounding part 38 is connected to a position on the input circuit 21 side of the output line 31 than the position of the grounding part 38.

[0037] Next, the operation of the power supply device 12 will be described.

[0038] When AC power is input from the AC power supply E, the AC power is input to the rectifier circuit 27 through the filter circuit 26, the AC voltage of the AC power is full-wave rectified by the rectifier circuit 27 to become a DC voltage, the rectified DC voltage is smoothed by the smoothing capacitor C1, and the DC power rectified and smoothed to a DC voltage is supplied to the power factor correction circuit 34.

[0039] In the power factor correction circuit 34, the switching element Q1 is turned on and off at a predetermined switching frequency by the control circuit 23, and the DC voltage of the rectified and smoothed DC power is boosted to a predetermined voltage. The boosted DC voltage is smoothed by the capacitor C2 and supplied to the constant current circuit 35.

[0040] In the constant current circuit 35, the control circuit 23 turns on and off the switching element Q2 at a predetermined switching frequency, and the DC voltage output from the power factor correction circuit 17 is stepped down and made constant current so as to become the lighting voltage of the light source 11. This constant current DC power is supplied to the light source 11, and the light source 11 is turned on.

[0041] While the light source 11 is turned on, the control circuit 23 performs feedback control (constant current control) on the switching operation of the switching element Q2 based on the value of the current flowing through the light source 11 so that the current supplied to the light source 11 becomes a constant current of a target value.

[0042] Moreover, the filter circuit 26 reduces noise generated by switching of the power conversion circuit 22, mainly the switching element Q1.

[0043] Here, a power supply device 12 of a comparative example is shown in a circuit diagram of Fig. 3 and a schematic diagram of a substrate 40 of Fig. 4. Note that the same reference numerals as those in this embodiment will be used in the explanation of the power supply device 12 of the comparative example.

[0044] The ground section 38 is disposed in the vicinity of the switching element Q1 between the input circuit 21 and the power conversion circuit 22 in order to accommodate the heat dissipation section 46 that dissipates heat from the switching element Q1. In this case, the ground section 38 is generally connected to a connection point P1 at which the switching element Q1 is connected to the low-potential output line 31.

[0045] In the power supply device 12 of this comparative example, as viewed from the input circuit 21 side, the current flows from the rectifier circuit 27 through connection point P1 of the output line 31, then returns to the input circuit 21 side, is connected to capacitors C4 and C5, and is grounded to the ground section 38. As a result, the distance to ground is long, the impedance of the pattern (output line 31) does not decrease, and current including noise components generated by the switching element Q1 does not flow easily, and the noise level is not sufficiently reduced.

[0046] As shown in FIG. 1, in the power supply device 12 of this embodiment, the grounding section 38 is connected to the output line 31 via capacitors C4 and C5 to a connection point P2 that is closer to the input circuit 21 than the connection point P1 to which the source of the switching element Q1 is connected.

[0047] Therefore, as seen from the input side, the rectifier circuit 27 is connected to the connection point P2 of the output line 31, and then to the capacitors C4 and C5, and then to the ground section 38. As a result, the distance to ground is short, the impedance of the pattern (output line 31) is reduced, and a current including noise components generated by the switching element Q1 flows more easily, thereby reducing the noise level.

[0048] Thus, in the power supply device 12 of the first embodiment, even if the ground part 38 is closer to the power conversion circuit 22 than the input circuit 21 and is disposed between the input circuit 21 and the power conversion circuit 22, noise can be reduced by connecting the ground part 38 to the output line 31 at a connection point P2 that is closer to the input circuit 21 than the connection point P1 to which the switching element Q1 is connected, or by connecting the ground part 38 to a position on the input circuit 21 side of the output line 31 than the position of the ground part 38. Therefore, it is possible to comply with the standard for radiated electric field strength of the Electrical Appliance and Material Safety Act without adding noise countermeasure components or the like.

[0049] Since the heat sink 46, which is thermally connected to the switching element Q1, is disposed in the ground section 38, the heat sink 46 can be used both for grounding to the power supply case and for dissipating heat from the switching element Q1, thereby reducing the number of parts.

[0050] Since a space region 43 is formed between the input circuit 21 and the power conversion circuit 22 on the substrate 40, this space region 43 can be used to arrange the ground portion 38 and the capacitors C4 and C5.

[0051] By disposing at least a part of the element portion 44 of the switching element Q1 in the space region 43, the element portion 44 can be thermally connected to the heat dissipation portion 46 that is disposed in the ground portion .

[0052] 5 is a schematic diagram of a board 40 of a power supply device 12 according to the second embodiment. Note that the same components as those in the first embodiment are given the same reference numerals and their description will be omitted.

[0053] 13 shows a case where the ground portion 38 is closer to the power conversion circuit 22 than the input circuit 21 and is within the area of ​​the power conversion circuit 22.

[0054] An element portion 44 of the switching element Q1 is disposed on the substrate 40 so as to extend from a position where the terminal 45 is connected to the substrate 40 toward the opposite side of the substrate 40 from the input circuit 21. The element portion 44 is disposed so as to be thermally connected to a heat dissipation portion 46 disposed in the ground portion 38.

[0055] In the power supply device 12 of the second embodiment as well, the ground part 38 is disposed closer to the power conversion circuit 22 than the input circuit 21, and the ground part 38 is connected to the output line 31 at a connection point P2 that is closer to the input circuit 21 than the connection point P1 to which the switching element Q1 is connected, or at a position on the output line 31 closer to the input circuit 21 than the position of the ground part 38, thereby making it possible to reduce noise. Therefore, it becomes possible to comply with the standard for radiated electric field strength in the Electrical Appliance and Material Safety Act without adding any noise countermeasure components or the like.

[0056] The ground portion 38 may be connected to the high potential side output line 30, or may be connected to both the high potential side output line 30 and the low potential side output line 31.

[0057] Moreover, the power supply device 12 is applied to the lighting device 10, but it can also be applied to other electrical devices.

[0058] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0059] 12 Power supply 20 Main circuit 21 Input circuit 22 Power Conversion Circuit 27 Rectifier circuit 30,31 Output lines 38 Grounding part 46 Heat radiation part C1 Smoothing capacitor Q1 Switching element C4, C5 capacitors P1 Attachment Point

Claims

1. a main circuit including: an input circuit having a rectifier circuit for rectifying input power and outputting the rectified power from the rectifier circuit to a pair of output lines; and a power conversion circuit connected to the output lines and having a switching element for converting the rectified power; a grounding section that is disposed closer to the power conversion circuit than the input circuit and is connected via a capacitor to the input circuit side than a connection point at which the switching element is connected to the output line; A power supply device comprising:

2. The ground portion is disposed between the input circuit and the power conversion circuit.

2. The power supply device according to claim 1 .

3. The ground portion is connected to a position on the output line closer to the input circuit than the position of the ground portion.

2. The power supply device according to claim 1 .

4. the input circuit has a smoothing capacitor connected to the output line of the rectifier circuit and smoothing the rectified power; The ground section is connected to the power conversion circuit side of the output line relative to the input circuit including the smoothing capacitor.

2. The power supply device according to claim 1 .

5. a heat sink disposed on the ground portion and thermally connected to the switching element; 5. The power supply device according to claim 1, wherein the power supply device is a power supply unit.

Images