JP2010004613A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device, wherein power consumption due to discharge resistance for reducing residual voltage is reduced. <P>SOLUTION: The power supply device includes: an across-the-line capacitor C1 and an across-the-line capacitor C2, which is higher in capacitance than the across-the-line capacitor C1; a line filter LF1 placed between the across-the-line capacitor C1 and the across-the-line capacitor C2 and a relay RLY1, that connects or disconnects the across-the-line capacitor C1 and the across-the-line capacitor C2 to and from each other; CPU that carries out control so as to disconnect the relay RLY1 during standby; and discharge resistance (resistor R6, resistor R7, resistor R8 and resistor R9), through which the current from the across-the-line capacitor C1 is passed at least during standby. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power supply device.

  In recent years, most power supply devices used in electronic devices are switching power supplies. In the switching power supply, from the viewpoint of miniaturization, the commercial AC power supply frequency is converted to a higher frequency (hereinafter referred to as a high frequency), and voltage conversion and constant voltage conversion are performed. Therefore, in such a switching power supply, a high-frequency current flows to the switching power supply, and as a result, there is a possibility that a noise signal is transmitted to the commercial AC power supply. Therefore, a noise filter is generally provided to prevent such a noise signal from flowing into the commercial AC power supply. This noise filter is generally composed of a line filter and an across capacitor. The across capacitor is a capacitor inserted at both ends of the commercial AC power supply. If the capacitance value is not large to some extent, the effect of suppressing noise does not occur. Therefore, the larger capacitance value is desirable from the point of noise suppression effect.

On the other hand, when the capacitance value of the across capacitor is large, the amount of charge stored in the across capacitor also increases. Many electronic devices using a switching power supply have a plug, and electric power is supplied to the electronic device by inserting the plug into an outlet. In this case, there is a risk of receiving an electric shock when a human body comes into contact with the plug immediately after the plug of the electronic device is unplugged from an outlet to which power from a commercial AC power supply is supplied. For this purpose, a discharge resistor, which is a discharge resistor, is provided in parallel with the across capacitor. Immediately after the plug is unplugged, the discharge current from the across capacitor is allowed to flow rapidly through the discharge resistor, and the charge accumulated in the across capacitor is Discharge to prevent electric shock.
JP 2008-43152 A

  However, when the electronic device is in operation, power from the commercial AC power supply flows directly into the discharge resistor, causing power loss. In particular, in a region where the voltage of the commercial AC power supply is 200 V or more (AC 200 V range), since the voltage of the commercial AC power supply is as high as about 200 V, the amount of power consumed by the discharge resistor is large. Furthermore, even when the electronic device is not used, there is a problem that power is consumed in the discharge resistor (standby power consumption), and wasteful power is consumed.

  In view of the above-described problems, the present invention provides a power supply device that reduces power consumption due to a discharge resistor for reducing the residual voltage.

  The power supply device of the present invention includes a first across capacitor, a second across capacitor having a capacitance value larger than that of the first cross capacitor, and a space between the first across capacitor and the second across capacitor. A line filter, a relay for connecting or disconnecting the first across capacitor and the second across capacitor, a control unit for controlling the relay to be disconnected during standby, and at least the standby And a discharge resistor through which a current from the first across capacitor flows.

  In the power supply device of the present invention, the capacitance value of the second across capacitor is made smaller than the capacitance value of the first across capacitor. Further, during standby, the first across capacitor and the second across capacitor are disconnected by a relay. In addition, since the discharge resistor through which the current from the first across capacitor flows is provided at least during the standby, the residual voltage can be reduced even if the value of the current flowing through the discharge resistor is small.

  According to the power supply device of the present invention, the value of the current flowing through the discharge resistor can be reduced, thereby reducing power consumption.

  FIG. 1 shows a main part of the power supply device of the embodiment. The power supply apparatus according to the embodiment includes a main power supply 10 and a standby power supply 20. For the main power supply 10, only the primary side circuit, which is the main part of the embodiment, is described.

  The power supply device of the embodiment includes an across capacitor C1 (first across capacitor) and an across capacitor C2 (second across capacitor) having a capacitance value larger than that of the across capacitor C1. In addition, a line filter LF1 is provided between the across capacitor C1 and the across capacitor C2. In addition, a relay RLY1 is provided that connects or disconnects the across capacitor C1 and the across capacitor C2. Moreover, the control part which controls so that the relay RLY1 is cut | disconnected at the time of standby is provided. Here, the control unit is composed of a CPU CPU. You may make it comprise with hardware. In addition, at least during standby, a discharge resistor (resistor R6, resistor R7, resistor R8, resistor R9) through which the current from the across capacitor C1 flows is provided.

  The main power supply 10 rectifies the AC power input from the plug PG with the rectifying element D1 to obtain DC power. As circuit components for this purpose, there are a plug PG, a fuse FU, a varistor VRS, an across capacitor C1, a line filter LF1, an across capacitor C2, a relay RLY1, a relay RLY2, a resistor R1, and a line filter LF2.

  Plug PG is inserted into an outlet (not shown) to guide the power from the commercial AC power source to the power supply device. The fuse FU prevents an overcurrent flowing through the power supply device. The varistor VRS prevents an overvoltage applied to the power supply device. Each of the across capacitor C1 and the line filter LF1, and each of the across capacitor C2 and the line filter LF2 prevents so-called common mode noise. Since the relay RLY1 is a feature of the embodiment, it will be described later. The resistor R1 is a resistor for preventing inrush current. The relay RLY2 is a switch in which a resistor R1, which is an inrush preventing resistor, is short-circuited by a switch after exhibiting the effect of suppressing the inrush current.

  The main power supply 10 includes a capacitor C3, an inductor L1, a power factor correction circuit PFC, a resistor R2, a resistor R3, a resistor R4, and a resistor R5 as circuit components from the rectifying element D1 to the output terminal of the power factor improving circuit PFC. Have.

  A smoothing filter is formed by the capacitor C3 and the inductor L1, and the pulsating power obtained by the rectifying element D1 is smoothed so as to obtain DC power. The power factor correction circuit PFC is a circuit for adjusting the phase of the alternating current flowing through the plug PG and the voltage applied to both ends of the plug PG to improve the power factor. A resistor R2, a resistor R3, a resistor R4, and a resistor R5 are load resistors of the power factor correction circuit PFC, and are stabilization resistors when a circuit unit of a device serving as a load is not connected to the main power supply 10.

  The standby power supply 20 is equivalently connected in parallel to the capacitor C1. Equivalently parallel means that the electric charge accumulated in the capacitor C1 is connected to the input side of the standby power supply 20 via the line filter LF1. With such a connection mode, a current from the capacitor C1 (first across capacitor) flows to the standby power supply 20.

  The standby power supply 20 is configured as a switching power supply, and includes a rectifying element D2, a capacitor C5, a switching power supply control circuit unit SWR, and a high-frequency transformer HT as main circuit components. A winding N1, winding N2, winding N3, and winding N4 are wound around the high-frequency transformer HT. A control circuit unit SWR is connected to the winding N1, and a rectifier circuit is connected to each of the winding N2, the winding N3, and the winding N4. The winding N2 is connected to a diode DD5 and a capacitor C6 as a rectifier circuit, the winding N3 is connected to a diode DD6 and a capacitor C7 as a rectifier circuit, and the winding N4 is connected to a diode DD7 as a rectifier circuit. A capacitor C8 is connected.

  The rectifier element D2 bridges the diodes DD1 to DD4 to rectify AC power from the commercial AC power supply, and the capacitor C4 smoothes the rectified voltage. This electric power is supplied to the control circuit unit SWR via the winding N1. The control circuit unit SWR generates high frequency power, and this high frequency power is applied to the winding N1. DC power is obtained by rectifying the high-frequency power obtained in the winding N2 by a rectifier circuit formed by the diode DD5 and the capacitor C6. This DC power is supplied to the power factor correction circuit PFC via the switch SW. The DC power obtained by rectifying the high-frequency power generated in the winding N3 by the rectifier circuit formed by the diode DD6 and the capacitor C7 is supplied to the control circuit unit SWR. The high frequency power obtained in the winding N3 is rectified by a rectifier circuit formed by a diode DD6 and a capacitor C7, and then supplied to the transmission side of the photocoupler PH via a resistor R11 and a resistor R12. Yes. The electric power obtained by the winding by the rectifier circuit formed by the diode DD7 and the capacitor C8 is supplied to the CPU CPU. The receiving side of the photocoupler PH is connected to the input port of the CP CPU, and the relay RLY1 and the relay RLY2 are connected to the output port of the CP CPU.

  The standby power supply 20 has a commercial AC power supply voltage detection circuit 21. The commercial AC power supply voltage detection circuit 21 includes a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, and a capacitor C4 as resistors for dividing the voltage. The resistor R10 and the capacitor C4 are connected in parallel, and the voltage across the resistor R10 is supplied to the control element IC1 that controls the current flowing through the photocoupler PH. Here, a DC voltage is generated at both ends of the resistor R10, and a DC voltage having a value corresponding to the voltage of the commercial AC power supply is generated.

  The standby power source 20 has a secondary side and a primary side. The winding N4, the diode DD7, the capacitor C8, the CPU CPU, and the photocoupler PH receiving side (detector side) are the secondary side. The part other than is the primary side.

  The characteristic part of embodiment is demonstrated in order. A relay RLY1 is provided in front of the across capacitor C2. During standby, which is a time when power is not supplied to the device connected to the main power supply 10, the switch circuit of the relay RLY1, the switch circuit of the relay RLY2, and the switch SW are in a disconnected state (OFF). During this standby time, the power factor correction circuit PFC is disconnected from the commercial AC power supply connected via the plug PG. The circuits important in the description of the embodiment in the connected state when viewed from the commercial AC power supply during standby are the commercial AC power supply voltage detection circuit 21, the standby power supply 20, and the across capacitor C1.

  Here, the commercial AC power supply voltage detection circuit 21 also serves as a discharge circuit for the across capacitor C1. At the same time that the plug PG is pulled out of the outlet, the charge of the across capacitor C1 is transferred to the fuse FU, one winding of the line filter LF1, the resistance R8, the resistance R9, the resistance R7, the resistance R6, and the path of one winding of the line filter LF1. Discharge at.

  Standards are defined for the time elapsed since the plug PG was removed and the residual voltage (the voltage across the plug PG). Here, a general theory of the relationship between the capacity of the across capacitor C1 and the residual voltage will be described. In order to reduce the value of the residual voltage, it is desirable to reduce the value of the capacity of the across capacitor C1. Further, in order to reduce the value of the residual voltage, it is desirable to reduce the value of the discharge resistor composed of the resistor R8, the resistor R9, the resistor R7, and the resistor R6 that functions as a discharge circuit. On the other hand, in order to reduce standby power, which is power consumed during standby, it is desirable to increase the value of the discharge resistor composed of the resistor R8, the resistor R9, the resistor R7, and the resistor R6 that functions as a discharge circuit. Further, in order to suppress noise flowing out from the power supply device to the commercial AC power supply side, it is desirable to increase the capacitance value of the across capacitor C1.

  The power supply apparatus according to the embodiment is a power supply apparatus that can solve the contradictions in characteristics required for each circuit element described above. Hereinafter, details of such a power supply device will be described in order.

  The resistor R5 and the capacitor C4 connected to the connection point between the resistor R7 and the resistor R9 are for detecting the voltage of the commercial AC power supply. A DC voltage corresponding to the voltage of the commercial AC power supply can be detected from both ends of the resistor R5 and the capacitor C4. There are two DC current paths through the commercial AC power supply voltage detection circuit 21. One of them is one end of the plug PG, a fuse FU, one winding of the line filter LF1, a resistor R8, a resistor R9, a resistor R10, a diode DD3, and a path from the other winding of the line filter LF1 to the other end of the plug PG. It is. The other is the other end of the plug PG, the other winding of the line filter LF1, the resistor R6, the resistor R7, the resistor R10, the diode DD4, one winding of the line filter LF1, and from the fuse FU to one end of the plug PG. This is the return path. These two paths change every half cycle of the commercial AC power supply. Since the current flowing in each half circuit flows in the same direction through the resistor R10, a DC voltage is generated across the capacitor C4. Here, the capacitor C4 connected in parallel to the resistor R10 functions as a smoothing capacitor, and a DC voltage corresponding to the voltage of the commercial AC power supply is generated at both ends of the capacitor C4.

  The commercial voltage secondary-side transmission circuit 22 formed with the photocoupler PH, the control element IC1, the resistor R11, and the resistor R12 will be described. The voltage generated in the capacitor C4 of the commercial AC power supply voltage detection circuit 21 is applied to the gate that is the control terminal of the control element IC1. When the voltage generated in the capacitor C4 exceeds a predetermined threshold, a current flows to the primary side which is the transmission side of the photocoupler PH (the output of the photocoupler PH is turned on), and a commercial AC power supply having a specified voltage value It can be detected that the voltage from is applied. Here, by appropriately determining the ratio of the resistance values of the resistor R11 and the resistor R12, the voltage of the commercial AC power source at which the output of the photocoupler PH is turned on can be set to an arbitrary value.

  The secondary circuit on the receiving side of the photocoupler PH is connected to the input terminal (IN) of the CPU CPU, and the CPU CPU can detect that the output of the photocoupler PH is turned on. Here, a 3.3V voltage is supplied to the CP CPU from a connection point between the diode DD7 and the capacitor C8, so that the operation is properly performed. The CP CPU confirms that the voltage from the commercial AC power supply is a specified voltage value, and prepares to turn on the main power supply 10. The CP CPU controls the switches of the relays in the order of the relay RLY1 and the relay RLY2 in accordance with a signal from the output terminal (OUT) of the CP CPU. As a result, the main power supply 10 is turned on. When the plug PG is removed from the outlet while the main power supply 10 is turned on, the primary side current of the photocoupler PH does not flow (the output of the photocoupler PH is turned off). Then, the CP CPU confirms this and controls the timing of disconnecting (OFF) the switch circuit of the relay RLY1 and the switch circuit of the relay RLY2. Here, the capacity of the capacitor C3, which is a smoothing capacitor of the main power supply 10, is such that the charge is accumulated until the switches of the relays RLY1 and RLY2 are turned off, and the above-described operation is performed without any problem. .

  In the power supply device of the embodiment, each of the main power supply 10 and the standby power supply 20 has a rectifier circuit, and two independent rectifier circuits are used. In this case, it is difficult to make the ground point (GND: reference voltage point) of each rectifier circuit the same. The reason is that since the current flowing through each diode used in each rectifier circuit varies depending on the forward voltage (Vf) of the diode, GND cannot be connected. Therefore, in the embodiment, the current flowing in the commercial AC power supply voltage detection circuit 21 is circulated through the rectifying element D2 of the standby power supply 20. The commercial AC power supply voltage determination circuit operates the control element IC1 functioning as a shunt regulator and the photocoupler PH using the power supplied from the winding N3 as the auxiliary winding of the high-frequency transformer HT of the standby power supply 20. ing. In this way, an interface between the photocoupler PH and the CP CPU is obtained.

  In the power supply device of the embodiment, 0.1 μF (micro farad) is used as the value of the across capacitor C1, 0.1 μF is used as the value of the capacitor C4, and 0.33 μF is used as the value of the across capacitor C2. Also, the value of the resistor R6 is 2.2 MΩ (Meg Ohm), the value of the resistor R7 is 2.2 MΩ, the value of the resistor R8 is 2.2 MΩ, the value of the resistor R9 is 2.2 MΩ, and the value of the resistor R10 is 220 kΩ ( Kilo ohm) is used.

  The standby power when the voltage input from the commercial AC power supply is 240 V is about 80 mW in the constants of the circuit shown in FIG. In this case, the voltage supplied to the CPU CPU was 3.3 V, and the current supplied to the CPU CPU was 2 mA. Further, the current supplied to the power factor correction circuit PFC was almost 0A.

(Comparative example)
FIG. 2 is a diagram illustrating a power supply circuit as a comparative example. The comparative example is a circuit conventionally used by the inventor described in the application of the present application. The superiority of the circuit of the embodiment will be specifically described by comparing the circuit shown in FIG. 1 with the circuit shown in FIG. 2, components having the same reference numerals as those in FIG. 1 are the same as those in FIG.

  Differences between the circuit shown in FIG. 1 and the circuit shown in FIG. 2 will be described below. The circuit shown in FIG. 2 has discharge circuits accumulated in the across capacitor C31 and across capacitor C32. The resistors R31, R32, and R33 of the commercial AC power supply voltage detection circuit 32 function as the discharge resistors. When the plug PG is inserted into an outlet (not shown), this discharge resistance is always a load connected to the commercial AC power supply through the resistor R1 which is an inrush current prevention resistor, including during standby. Here, the resistance value of the resistor R1 is relatively small because it limits the magnitude of the inrush current. The value of the resistor R1 is smaller than that of the resistors R31, R32, and R33, and the error in detecting the commercial AC power supply voltage is a negligible resistance value. In the conventional example adopted by the inventor, the charge accumulated in 0.44 μF obtained by adding the capacity of the across capacitor C31 (0.22 μF) and the capacity of the across capacitor C32 (0.22 μF) is discharged. For this reason, the value of the discharge resistance formed by the resistor R31, the resistor R32, and the resistor R33 described above must be reduced, and as a result, the power consumption is large.

  Similarly, the PFC overvoltage protection detection resistors R2, R3, R4, and R5 are loads connected to the commercial AC power source through the resistor R1. Here, the resistance value of the resistor R1 is smaller than the resistors R2, R3, R4, and R5 and can be ignored. Usually, the values of the resistor R2, the resistor R3, the resistor R4, and the resistor R5 are required to be a predetermined value or less in order to ensure stable operation of the power factor correction circuit PFC. The power consumed by this resistor is also large, and the power consumed by the primary side with such a load is much larger than 0.1 W.

  In the circuit shown in FIG. 2, both the across capacitor C31 and the across capacitor C32 are always connected to the discharge resistor including the standby time, and the addition capacitance of both is 0.44 μF. On the other hand, in the circuit shown in FIG. 1, during standby, the value of the across capacitor C1 connected to the discharge resistor is as small as 0.1 μF. Here, the values of the across capacitor C31 and across capacitor C32 in the circuit in FIG. 2 can obtain the same effect as the noise suppression effect exhibited by the across capacitor C1 and across capacitor C2 in the circuit in FIG. Is set.

  It is necessary to make the magnitude of the residual voltage after a predetermined elapsed time after the plug PG is removed in the circuit shown in FIG. 2 equal to the magnitude of the residual voltage after the same predetermined elapsed time in the circuit shown in FIG. . As described above, the value of the discharge resistance in the circuit shown in FIG. 2 must be smaller than the value of the discharge resistance in the circuit shown in FIG. For the above reasons, the power consumed by the primary side is large in the circuit shown in FIG.

  The power supply device according to the embodiment has the following features in order to reduce power consumption during standby. When the plug PG is connected to an outlet, the capacity of the across capacitor connected to the commercial AC power supply circuit is always small even during standby. That is, the across capacitor C1 and the across capacitor C2 are separated by the relay RLY1. In this way, only the across capacitor C1 is connected to the commercial AC power supply circuit during standby. During standby, the power consumption of the power supply circuit is small, so that noise generation is also smaller than during high power consumption when the device operates. Therefore, even if the capacity of the across capacitor C1 is small, the noise suppressing effect can be sufficiently exhibited. By doing so, a sufficient effect can be obtained even if the value of the discharge resistance for discharging the charge stored in the across capacitor C1 is increased from the viewpoint of preventing the electric shock described above. As a result, the amount of power consumed by the discharge resistor can be reduced, and the power consumption during standby can be reduced.

  Further, in the power supply device of the embodiment, as a discharge resistor, power is not simply lost by using only the resistor but also by supplying power to the standby power source 20 from both ends of the across capacitor C1 through the rectifier element D2. Yes. That is, the standby power supply 20 that needs to be energized even during standby functions as the discharge resistance of the across capacitor C1. In this way, the residual voltage after the plug PG is pulled out from the outlet by causing the current flowing through the standby power supply 20 to contribute to the discharge of the across capacitor C1 while increasing the resistance value of the discharge resistor formed by the resistor. Can be reduced rapidly. In this regard, since the conventional circuit shown in FIG. 2 discharges only with the discharge resistor, when the value of the discharge resistor is reduced, the heat generated by the resistor also increases and wastes power. Moreover, the shape of the discharge resistance has also increased. Since the discharge resistance can be made high in this way, standby power can be greatly reduced during standby when the subsequent circuit is disconnected by the relay RLY1.

  As described above, in the power supply device of the embodiment, the standby power supply 20 is connected to the across capacitor C1 (in the embodiment, via the line filter LF1), and as described above, the power consumption during standby is reduced. We are trying to reduce it. However, when such a configuration is adopted, the DC power rectified in the main power supply 10 cannot be used in the standby power supply 20. The main power supply 10 and the standby power supply 20 each need a rectifier circuit that rectifies AC power from a commercial AC power supply independently. Further, the main power supply 10 and the standby power supply 20 operate in a coordinated manner by having a common connection point (GND) in the circuit after rectification. On the other hand, since the commercial AC power supply side of the main power supply 10 and the standby power supply 20 also has a common connection point as described above, even if the common connection point is connected in the rectified circuit, the circuit operation Clearly, this is not done properly. In the embodiment, from this point, the commercial voltage secondary transmission circuit 22 uses the photocoupler PH to optimize the circuit operation.

  In the power supply device of the embodiment, there is an effect of reducing power consumption regardless of the voltage of the commercial AC power supply, but in particular, when the commercial power supply voltage is used in an area where the commercial power supply voltage is about 200 V (AC 200 V range), the residual voltage Therefore, the effect of reducing power consumption is particularly great. If the embodiment is adopted, it is possible to reduce the standby power of the power supply apparatus to 0.1 W or less, which has been extremely difficult in the past. Also, in the AC 200V range, the voltage discharge across the plug after the plug is removed from the outlet is fast. If the circuit of the embodiment is compared with the circuit that the inventor has conventionally implemented, the circuit of the embodiment can be implemented with minimal component changes with respect to the conventional circuit, so that the burden on the apparatus cost is small.

It is a figure which shows the power supply device of embodiment. It is a figure which shows the power supply device of a comparative example.

Explanation of symbols

  10 main power supply, 20 standby power supply, 21, 32 commercial AC power supply voltage detection circuit, 22 commercial voltage secondary side transmission circuit, C1, C2, C31, C32 across capacitor, C3, C4, C5, C6, C7, C8 capacitor, CPU CP, D1, D2 Rectifier, DD1, DD2, DD3, DD4, DD5, DD6, DD 7 Diode, FU fuse, HT High frequency transformer, IC1 control element, L1 inductor, LF1, LF2 Line filter, N1, N2, N3 , N4 winding, PFC power factor correction circuit, PG plug, PH photocoupler, R1, R10, R11, R12, R2, R3, R31, R32, R33, R4, R5, R6, R7, R8, R9 resistance, RLY1 , RLY2 relay, SW switch Pitch, SWR control circuit unit, VRS varistor

Claims (3)

A first across capacitor;
A second across capacitor having a larger capacitance value than the first cross capacitor;
A line filter disposed between the first across capacitor and the second across capacitor;
A relay for connecting or disconnecting the first across capacitor and the second across capacitor;
A control unit that controls to disconnect the relay during standby;
And a discharge resistor through which a current from the first across capacitor flows at least during the standby.   The power supply apparatus according to claim 1, further comprising a standby power supply through which a current from the first across capacitor flows at least during the standby. Furthermore, a commercial AC power supply voltage detection circuit for detecting the voltage of the commercial AC power supply,
The power supply device according to claim 2, further comprising a commercial voltage secondary-side transmission circuit having a photocoupler that informs the control unit that the voltage from the commercial AC power supply voltage detection circuit is a predetermined value.

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