KR20110010232A - Power supply apparatus with discharge circuit of capacitor - Google Patents

Abstract

PURPOSE: A power supply device is provided to prevent the electric shock accident of a user by discharging the voltage of a PFC(Power Factor Correction) capacitor when power is disconnected. CONSTITUTION: A power supply device comprises a rectifying circuit part(10), a PFC circuit part(30), a main capacitor(C1), and a discharge control part(50). The rectifying circuit part converts AC power into DC power. The PFC circuit part converts a DC voltage into a predetermined voltage level. The main capacitor is connected between the output terminal of the PFC circuit part and a low electric potential. The main capacitor smoothes the DC power outputted through the PFC. The discharge control part discharges a voltage which is charged in the main capacitor when power is disconnected.

Description

Power supply with capacitor discharge circuit {POWER SUPPLY APPARATUS WITH DISCHARGE CIRCUIT OF CAPACITOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply, and more particularly, to a power supply having a capacitor discharge circuit for controlling charging / discharging of a capacitor for power factor correction in a power supply.

In general, a high output power supply rated at 250W or higher may include a power factor correction circuit (hereinafter referred to as a PFC), which is a power saving circuit for improving power efficiency of a power supply. .

The superior PFC method is a sinusoidal input line current-free harmonic with almost unique power factor over a wide range of loads, good wiring and load regulation with correct output dynamics, small size, low weight, small component count, economy, and high power conversion. Efficiency, low EMI.

In addition, they must be within the range of typical AC input voltages and have a wide range of output voltages from low output ripple and very low DC outputs (eg 12V, 24V, etc.) to high voltages (eg 800V). More preferred.

The PFC can control power to components such as transformers, ballasts, and converters that are concerned about instantaneous power leakage, thereby supplying more stable current to each component and preventing unnecessary power consumption.

A large capacity smoothing capacitor is disposed at the rear end of the PFC. In the case of the capacitor, a constant voltage is charged even when the power is turned off, thereby causing an electric shock when a user or the like contacts the product.

The present invention is to provide a power supply having a capacitor discharge circuit for discharging the voltage charged in the PFC (Power Factor Correction) capacitor when the power supply is powered off.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above may be clearly understood by those skilled in the art from the following description. There will be.

Technical means of the present invention for achieving the above object, the rectifier circuit unit for converting the AC power input from the outside into DC power; A PFC circuit unit for converting a DC voltage input from the rectifier circuit unit into a predetermined voltage level; A main capacitor connected between an output terminal of the PFC circuit unit and a low potential to smoothly output a DC power output through the PFC circuit unit; And a discharge control unit configured to discharge the voltage charged in the main capacitor when the power is turned off.

Specifically, the discharge control unit is a switching unit connected in parallel with the main capacitor and switched in accordance with the input control signal; A first potential generator configured to set a power-related signal input from the outside to have a predetermined voltage level; A second potential generator configured to set the externally related power supply signal to have a predetermined voltage level; A low voltage delay unit for delaying the drop of the output voltage of the second potential generating unit when a low signal is input from the outside; And a comparator configured to receive the signals output from the first potential generating unit and the second potential forming unit as input terminals and non-inverting terminals, respectively, and output a low signal or a high signal to the switching unit according to the comparison result. Characterized in that.

As described above, the present invention discharges the voltage charged in the PFC (Power Factor Correction) capacitor when the power is turned off, thereby preventing electric shock even when the power is turned off, thereby increasing the reliability of the product. There is an advantage.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention. Like elements in the figures are denoted by the same reference numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a view showing a power supply having a capacitor discharge circuit according to an embodiment of the present invention, the power supply 1 is a rectifier circuit portion 10, PFC circuit portion 30, the main capacitor (C1) and the discharge control unit It consists of 50.

The rectifier circuit part 10 is a circuit part such as a full bridge diode that converts an AC power source from which noise is removed from the outside into a DC power source.

The PFC circuit unit 30 converts the DC voltage input from the rectifying circuit unit 10 to a suitable predetermined voltage level and outputs it. The PFC circuit unit 30 is a power factor correction unit (PFC) including a coil, a switching element, a rectifying diode, and the like.

The main capacitor C1 is connected between the output terminal Vout and the low potential Vss of the PFC circuit unit 30 to smooth the DC power outputted through the PFC circuit unit 30 to convert the DC (DC / DC converter, inverter). Output to a circuit such as

That is, the input AC power is rectified by the rectifying circuit unit 10 and converted into DC power, and the converted DC power is converted to a predetermined voltage level through the PFC circuit unit 30 and then through the smoothing capacitor C1. Output after smoothing. Accordingly, the input DC voltage is converted into a high level DC voltage by the PFC circuit unit 30 and the smoothing capacitor C1 and output.

The discharge controller 50 is configured to discharge the voltage charged in the main capacitor C1 when the power supply device is turned off (standby state), and the discharge controller 50 includes the switching unit 51 and the first potential generator. (53), the second potential forming portion (55), the low voltage delay portion (57) and the comparator (59).

The switching unit 51 is connected to the current path between the output terminal (Vout) and the low potential (Vss) of the PFC circuit unit 30 is connected in parallel with the main capacitor (C1) N channel that is switched in accordance with the input control signal MOSFET transistor S1 and an antiparallel diode D1 connected in parallel to the transistor S1 in parallel.

The first potential generator 53 is configured to set the power-on and off-related signals input from the outside to have a predetermined voltage level. The plurality of resistors R1, which divides the voltage of the input power-related signal, R2).

The second potential forming unit 55 sets the power on / off related signal input from the outside to have a predetermined voltage level. The second potential forming unit 55 divides the voltages of the input power on / off related signals. R4).

Here, the same signal is input to the first potential generator 53 and the second potential generator 55, and the first potential generator 53 is a power source on / off signal related to the second potential generator. It is preferable to set the respective resistance values R1 to R4 so as to have a higher potential than the forming portion 55. That is, when the 'high' signal is input from the outside, the first potential generating unit 53 selects each resistance value to have a higher output voltage than the second potential forming unit 55.

The low voltage delay unit 57 is connected between the output terminal of the second potential generating unit 55 and the low potential so that when a low signal (when the power is turned off) is input from the outside, It may be configured as a capacitor (C2) for delaying the output voltage drop to a low voltage. That is, the low voltage delay unit 57 charges when a high signal is input from the outside, and gradually lowers the output voltage of the second potential forming unit 55 to a low voltage when a low signal is input from the outside.

The comparator 59 receives and compares the signals output from the first potential generator 53 and the second potential generator 55 with the inverting terminal (-) and the non-inverting terminal (+), respectively, according to the comparison result. The low signal or the high signal is output to the switching unit 51.

Then, the operation of the discharge control unit 50 will be described with reference to the waveform diagram of FIG. 2.

First, since the resistance values R1 / R2 and R3 / R4 are set so that the potential of the first potential generating portion 53 is higher than the potential of the second potential forming portion 55, the power supply voltage is connected to the power supply from the outside. When the high signal is input, the output voltage of the comparator 59 becomes a low signal because the value of the output voltage V1 of the first potential generator 53 is greater than the output voltage V2 of the second potential generator 55. . Accordingly, the switching unit 51 is turned off so that the fifth resistor R5 is in a floating state.

On the other hand, when a low signal related to power-off is input from the outside, the output signal of the first potential generator 53 becomes a low signal. However, since the output of the second potential generating unit 55 gradually drops to the low voltage by the low voltage delay unit 57, that is, the charging voltage of the capacitor C2, a section higher than V1, which immediately becomes 0 V at power-off, It will exist. At this time, as the comparator 59 outputs a high signal to turn on the transistor S1 of the switching unit 51, the voltage charged in the main capacitor C1 is pulled down to a low potential through the current path of the transistor S1. And discharged.

As described above, in the present invention, all the voltages charged in the main capacitor C1 of the PFC are discharged when the power is turned off, thereby preventing an electric shock that may occur when the power-off is in contact with the product.

The present invention has been described with reference to the preferred embodiments, and those skilled in the art to which the present invention pertains to the detailed description of the present invention and other forms of embodiments within the essential technical scope of the present invention. Could be. Here, the essential technical scope of the present invention is shown in the claims, and all differences within the equivalent range will be construed as being included in the present invention.

1 is a circuit diagram showing a power supply having a capacitor discharge circuit according to an embodiment of the present invention.

2 is a waveform diagram illustrating an operation of the discharge control unit of FIG. 1.

* Explanation of symbols for the main parts of the drawings

10: rectifier circuit portion 30: PFC circuit portion

C1: main capacitor 50: discharge control unit

51: switching unit 53: first potential generating unit

55: second potential generator 57: low voltage delay unit

59: comparator

Claims (7)

Rectification circuit unit for converting AC power input from the outside into DC power; A PFC circuit unit for converting a DC voltage input from the rectifier circuit unit into a predetermined voltage level; A main capacitor connected between an output terminal of the PFC circuit unit and a low potential to smoothly output a DC power output through the PFC circuit unit; And And a discharge control unit for discharging the voltage charged in the main capacitor when the power is turned off. The method of claim 1, wherein the discharge control unit A switching unit connected in parallel with the main capacitor and switched according to an input control signal; A first potential generator configured to set a power-related signal input from the outside to have a predetermined voltage level; A second potential generator configured to set the externally related power supply signal to have a predetermined voltage level; A low voltage delay unit for delaying the drop of the output voltage of the second potential generating unit when a low signal is input from the outside; And A comparator configured to compare the signals output from the first potential generating unit and the second potential forming unit with the inverting terminal and the non-inverting terminal, respectively, and output a low signal or a high signal to the switching unit according to the comparison result; Power supply having a capacitor discharge circuit. The method of claim 2, And the first potential generator is set to have a higher potential than a second potential generator for a power-related signal input from the outside. The method of claim 2, wherein the first dislocation forming unit A power supply having a capacitor discharge circuit including a plurality of resistors for distributing the voltage of the power-related signal input from the outside. The method of claim 2, wherein the second dislocation forming unit A power supply having a capacitor discharge circuit including a plurality of resistors for distributing the voltage of the power-related signal input from the outside. The method of claim 2, wherein the low voltage delay unit And a capacitor discharge circuit including a capacitor connected between the output terminal of the second potential generator and a low potential. The method of claim 2, The switching unit has a capacitor discharge circuit including an N-channel MOSFET transistor.

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