KR101564004B1 - AC-DC converter - Google Patents

Abstract

An AC-DC converter is disclosed. The AC-DC converter according to a preferable embodiment of the present invention outputs DC power which is not smoothed after the rectification of AC power to an output terminal, to which the loads of electronic appliances are linked; uses the non-smoothed DC power to charge one or more capacitors contained in a charge unit with power; detects zero crossing points of inputted AC power; and discharges the voltage applied to the charge unit to the output terminal as the voltage of DC power outputted to the output terminal has tendency to go down and falls below a predetermined reference voltage value, that is, around at a zero crossing point to increase the voltage of the output terminal, thereby smoothing the DC of the output terminal. Accordingly, rectified power is smoothed without using an electrolyte capacitor having a large volume and low reliability of elements, thereby providing an AC-DC converter suitable for miniaturization, which can ensure higher reliability.

Description

DC converter (AC-DC converter)

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a DC converter, and more particularly, to a DC converter that does not smooth by connecting an electrolytic capacitor to a DC to a DC smoothing.

A DC converter that converts AC power to DC power is a device that is installed in almost all electronic devices such as a TV and a refrigerator and rectifies AC power supplied from a commercial power source to DC to provide an internal load. Therefore, various requirements are being raised. For example, as a product is miniaturized, the DC conversion device has been expected to be miniaturized and improved in durability with high efficiency.

In a conventional DC converter, a switching mode power supply (SMPS) is generally used to supply a stable DC power to a user's device. However, when the AC power is converted into the DC power using the SMPS described above, a problem arises in that a stable DC power can not be supplied to the user's device.

Also, since the SMPS uses a large-capacity electrolytic capacitor in the primary, secondary, or secondary side of the circuit in order to reduce the voltage ripple included in the non-smoothed direct-current power after converting the AC power to DC, And the failure of the electrolytic capacitor at the time of use for a long time causes a problem that the entire device including the DC converter is broken.

Therefore, there is a need for a DC converter capable of supplying a stable DC power to a user's device while at the same time smoothing a non-smoothed DC power without using a large-capacity electrolytic capacitor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a DC converter capable of smoothing a DC-converted power source without using a bulky electrolytic capacitor, thereby reducing the size of a DC converter and a device including the DC converter, And to provide a DC converter capable of securing the DC converter.

According to an aspect of the present invention, there is provided a DC converter comprising: a rectifier for rectifying an input AC power and outputting an unshielded DC power to an output terminal; A charging unit to be charged using power outputted from the rectifying unit; A discharging switching unit for connecting the charging unit to the output terminal according to a discharge control signal and discharging the power charged in the charging unit to the output terminal to smooth the output voltage of the output terminal; And a discharge control unit for outputting the discharge control signal when the voltage of the output terminal falls below a predetermined discharge reference value.

According to another preferred embodiment of the present invention, the charging unit includes a plurality of capacitors provided in parallel, and the discharge switching unit includes a plurality of discharge switches each connecting the plurality of capacitors and the output terminal, The control signal may be respectively output to the plurality of discharge switches to turn on the plurality of discharge switches sequentially.

According to another preferred embodiment of the present invention, the DC / DC converter includes a zero phase detector for receiving an AC power input to the rectifier and outputting a zero crossing point; And a setting unit for outputting the discharge reference value according to a setting of a user, wherein the discharge control unit is in a trend of lowering the voltage of the output terminal by using the zero crossing point and the discharge reference value input from the zero phase detection unit, When the voltage of the output terminal becomes the discharge reference value or less, the discharge control signal can be outputted.

According to another preferred embodiment of the present invention, the charging unit includes a plurality of capacitors provided in parallel, and the discharge switching unit includes a plurality of discharge switches each connecting the plurality of capacitors and the output terminal, The control unit outputs the discharge control signal so that one of the plurality of capacitors is discharged when the voltage of the output terminal becomes the discharge reference value or less. When the voltage value raised by the discharged capacitor again falls below the discharge reference value, So that the voltage of the output terminal is maintained to be equal to or higher than the discharge reference value.

According to another preferred embodiment of the present invention, the charging unit includes: a plurality of diodes each having an anode connected to the rectifying unit and a cathode connected to one end of the capacitor; And a plurality of capacitors connected to the cathode of the diode and grounded at the other end, wherein the discharge switching unit has a plurality of discharge switches each having one end connected to the output terminal and the other end connected to the cathode of the diode and a connection node of the capacitor can do.

According to another preferred embodiment of the present invention, the DC-DC converter further includes an output voltage detector for distributing the voltage of the output terminal to the discharge controller, and the discharge controller may control the voltage The magnitude of the voltage at the output terminal can be calculated.

In addition, according to another preferred embodiment of the present invention, the direct current converting apparatus outputs the un-smoothed direct current power outputted from the rectifying section to the output terminal, and when the charge control signal is inputted, And a charging switching unit for charging the capacitors included in the charging unit.

According to another preferred embodiment of the present invention, the charge switching unit includes an inductor connected to the rectifying unit, a diode connected to the inductor, for blocking a current discharged from the charging unit from flowing to the rectifying unit, And a charging switch element having one end connected to the node between the diodes and the other end connected to one or more capacitors included in the charging section.

According to another preferred embodiment of the present invention, the DC-DC converter receives the AC power input to the rectifying unit and receives the zero crossing point from the zero phase detecting unit zero phase detecting unit for outputting the zero crossing point, Further comprising a charge control unit for receiving the duty ratio reference value from the charge control unit and for charging the charge unit by outputting the charge control signal implemented by the PWM signal to the charge switch device, And the duty ratio is set to be smaller as the peak value of the input power is closer to the output power, the charge control signal can be output.

According to another preferred embodiment of the present invention, the discharge control unit outputs the charge inhibition signal to the charge control unit while discharging the charger unit, and the charge control unit outputs the charge control signal to the charge switching unit can do.

The DC converter according to a preferred embodiment of the present invention rectifies an AC power to output an unshielded DC power to an output terminal to which loads of the electronic apparatus are connected, When one or more capacitors are charged with power and then the zero crossing point of the input AC power is detected and the voltage of the DC power outputted to the output terminal is lowered and falls below a preset reference voltage value, In the vicinity of the point, the voltage charged in the charger is discharged to the output terminal to increase the voltage of the output terminal, thereby smoothing the DC power of the output terminal.

As described above, the present invention can provide a DC conversion device which is suitable for miniaturization of a product and is more reliable by smoothing a rectified power source without using an electrolytic capacitor having a large volume and low reliability of the device.

1 is a block diagram showing the configuration of a direct current converting apparatus according to a preferred embodiment of the present invention.
2 is a diagram showing a voltage waveform of an input power source input to a DC converter according to a preferred embodiment of the present invention and a voltage waveform of an output power source output from the DC converter.
FIG. 3 is a diagram showing a more specific configuration of a DC-DC converter according to a preferred embodiment of the present invention.

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

FIG. 1 is a block diagram showing the configuration of a direct current converting apparatus according to a preferred embodiment of the present invention. FIG. 2 is a block diagram of a voltage waveform of an input power source input to a direct current converting apparatus according to a preferred embodiment of the present invention, FIG. 3 is a diagram showing a more detailed configuration of a DC-DC converter according to a preferred embodiment of the present invention.

1, a DC converter according to a preferred embodiment of the present invention includes a rectifier 10, a charge switch 20, a discharge switch 30, a charger 40, an output voltage detector 50, A phase detection unit 60, a charge control unit 70, a discharge control unit 90, and a setting unit 80.

The rectifying unit (10) rectifies the AC input power and outputs the smoothed DC power to the charge switching unit (20). The rectifying unit 10 may be implemented by a general bridge rectifying circuit, but is not limited thereto.

The charge switching unit 20 receives the smoothed direct current power from the rectifier 10 and outputs the input direct current power to an output terminal Vout to which the loads of the electronic devices installed in the direct current converters of the present invention are connected And outputs the non-smoothed direct current power inputted from the rectifying section 10 to the charging section 40 to charge the capacitor inside the charging section 40 according to the charging control signal inputted from the charging control section 70. [

At this time, the charge control signal input from the charge control unit 70 to the charge switching unit 20 may be implemented as a PWM (Pulse Width Modulation) signal, and the charge switching unit 20 may charge the internal charge The switching element Q1 is turned on / off to supply power to the charging unit 40 or to cut off the power supply to charge the capacitor inside the charging unit 40. [ Here, the charge switching unit 20 includes an inductor L1 to boost the input DC voltage to prevent the level of the input DC voltage from dropping.

The charging unit 40 is implemented to include one or more capacitors. When the charging switching unit 20 is in the ON state, the charging unit 40 is supplied with the DC power outputted from the rectifying unit 10, When the charging unit 40 is connected to the output terminal, the power charged in the capacitor is discharged to the output terminal to smooth the non-smoothed power output from the rectifying unit 10 to the output terminal.

The discharge switching unit 30 includes one or more switches, one end of which is connected to a capacitor included in the charging unit 40, and the other end of which is connected to the output terminal Vout. Each switch included in the discharge switching unit 30 is turned on / off according to a discharge control signal input from the discharge control unit 90 to connect or disconnect the output unit and the charger unit 40.

The output voltage detector 50 is implemented by voltage dividing resistors, detects and scales the voltage output through the current output terminal, and outputs the voltage to the discharge controller 90.

The zero phase detector 60 receives the same input power as the rectifier 10 and detects the time point when the voltage of the input power source is zero and outputs the zero phase to the charge controller 70 and the discharge controller 90 . The zero phase detecting unit 60 includes a rectifying circuit for rectifying the input power to rectify the input power to the setting unit 80 in the same manner as the rectifying unit 10, (80).

The setting unit 80 is implemented as a variable resistor so that the discharge control unit 90 outputs a discharge reference voltage value (discharge reference value) to be discharged by the capacitors included in the charging unit 40, The control unit 70 outputs a duty ratio reference value for setting the frequency of the PWM control signal to be output to the charge switching unit 20. [ For example, when the user wants to keep the lowest voltage value of the output terminal at 100V, the user sets the resistance value of the setting unit 80 to output the discharge reference value corresponding to 100V to the discharge control unit 90. [

The charge control unit 70 outputs the PWM charge control signal to the charge switching unit 20 using the zero phase timing input from the control phase detector 60 and the duty ratio reference value input from the setting unit 80, ).

The charging control unit 70 gradually decreases in a period in which the voltage of the input power source output from the rectifying unit 10 increases from the time when the duty ratio of the PMW charging control signal is detected to the zero phase and the magnitude of the voltage of the input power source reaches the peak The PWM control signal is generated so as to increase the duty ratio again, and the PWM control signal is output to the charge switching unit 20.

The discharge control unit 90 receives a zero phase timing point (i.e., a time point at which the voltage value of the input power source becomes 0) from the zero phase detection unit 60 and determines whether the voltage value of the current input power source increases or decreases .

The discharge control unit 90 receives the discharge reference value for discharging the charging unit 40 from the setting unit 80 and calculates the voltage value of the current output terminal by using the output voltage value inputted from the output voltage detection unit 50 When the voltage value of the current output terminal is less than the discharge reference value, the discharge control signal is outputted to the discharge switching unit 30 and the power stored in the charging unit 40 is discharged to the output terminal To prevent the output voltage from dropping below 100V, as shown in the output voltage waveform of FIG.

In the example shown in FIG. 2, it can be seen that the charging unit 40 includes three capacitors, and the discharge controller 90 has three capacitors sequentially discharged to smooth out the output voltage.

FIG. 3 is a diagram showing a more specific configuration of a DC-DC converter according to a preferred embodiment of the present invention. 3, the configuration and operation of the DC-DC converter according to the preferred embodiment of the present invention will be described in more detail.

Referring to FIG. 3, the rectifying unit 10 of the DC-DC converter according to the preferred embodiment of the present invention is implemented as a general bridge rectifying circuit and receives rectified AC power, .

로 설정하였음).The charge switching section 20 is implemented with an inductor L1, a diode D1, and a charge switch element Q1. The inductor L1 is connected to the rectifying unit 10 to prevent the voltage level of the unscaled input power from being lowered from the rectifying unit 10. The input power from the inductor L1 is supplied to the diode The inductor L1 is output to the output terminal via the switching element D1 and is output to the charging switch element Q1

.

The charge switch element Q1 may be implemented by a commonly used switch element such as an FET switch and may be turned on or off according to a PWM charge control signal input from the charge controller 70 to turn on the inductor L1 And outputs the passed input power to the charging unit 40 to charge the capacitors C1 to C3 included in the charging unit 40. [

The charging unit 40 is implemented to include one or more capacitors C1 to C3 and each of the capacitors C1 to C3 has one end connected to the discharging switches S2 to S4 and the charging switch unit (Q1) and the other end is grounded. Diodes D2 to D4 are provided between the capacitors C1 to C3 and the charging switch element Q1 to prevent current from flowing backward when discharging the capacitors C1 to C3. The anode of the diodes D2 to D4 is connected to the charging switch element Q1 and the cathode of the diodes D2 to D4 is connected to the node between the capacitors C1 to C3 and the discharging switches S2 to S4.

In the example shown in Fig. 3, three capacitors (the first capacitor c1 to the third capacitor c3) are provided in parallel to be charged at the same time as the voltage level of the input power source rises, Is sequentially switched on by the discharge control signal input from the discharge control unit 90 to discharge the power charged in the output terminal to the output terminal to prevent the output voltage from dropping down to zero potential along the input power source. In the example shown in Fig. 3, the capacity of the first condenser c1 is set to 1 kPa, the capacity of the second condenser c2 is set to 2 kPa, and the capacity of the third condenser c3 is set to 2 kPa.

The discharge switching unit 30 includes one or more discharge switches S2 to S4. Each switch is connected to the capacitors C1 to C3 included in the charging unit 40 at one end thereof. The other end of the switches is connected to the output terminal Vout, Lt; / RTI > Discharge switches S2 to S4 can be implemented with common switch elements such as FET switches. In the example shown in Fig. 3, the discharge switching unit 30 is implemented to include three discharge switches S2 to S4 connected to the three capacitors C1 to C3, respectively, and each of the discharge switches S2- S4 are switched on when a discharge control signal is inputted from the discharge control unit 90 to connect the capacitors C1 to C3 of the charger unit 40 and the output terminal so that the charging power of the capacitors C1- .

2, peak voltages of reference numerals 201, 211, and 221 are output waveforms formed by discharging the first capacitor c1, and peak voltages of 202, 212, and 222 are respectively connected to the second capacitor c2. And peak voltages of 203, 213, and 223 are output waveforms formed by discharging the third capacitor c3, respectively.

The output voltage detector 50 is implemented as distribution resistors that distribute the output voltage, detects and scales the voltage output through the current output terminal, and outputs the voltage to the discharge controller 90. 3, the resistance value of the first resistor R1 corresponds to about 9 times the resistance value of the second resistor R2, and therefore, the output voltage detector 50 detects the voltage waveform applied to the output terminal Scales the voltage of the same waveform to 1/10 and outputs it to the discharge controller 90.

The setting unit 80 is implemented by two variable resistors VR1 and VR2 and the capacitors C1 to C3 included in the charging unit 40 perform discharging in the discharge control unit 90 The charge control unit 70 outputs a duty ratio reference value for setting the frequency of the PWM control signal to be output to the charge switching unit 20. [ The user can set the voltage value of the output terminal at which discharging of the capacitors C1 to C3 is performed by adjusting the resistance value of VR1 and adjust the resistance value of VR2 so that the PWM The duty ratio of the control signal can be adjusted.

2 and 3, the operation of the DC converter according to the preferred embodiment of the present invention will be described.

First, the user sets the duty ratio of the discharge reference value and the charge control signal, which are voltage values at which the capacitors C1 to C3 of the charging unit 40 are discharged, by adjusting the variable resistance value of the setting unit 80. [ Here, the voltage value at which the capacitors C1 to C3 are discharged refers to a minimum voltage level provided from the output terminal to the load side of the electronic device in a steady state. In the example shown in FIG. 3, about 100 V is a discharge voltage value Discharge reference value.

Thereafter, AC power is applied to the rectifying section 10 and the zero phase detecting section 60, respectively.

The rectifying unit 10 rectifies the AC power to output a non-smoothed DC power as shown in FIG. 2A to the charge switching unit 20. [ The zero phase detector 60 detects the zero crossing point of the input AC power and outputs the detected zero crossing point to the charge controller 70 and the discharge controller 90. The zero phase detector 60 outputs the zero crossing point of the input AC power to the charge controller 70 and the discharge controller 90, And outputs the reference voltage Ref V to the setting unit 80. [

The charge controller 70 receives the time information of the zero crossing point from the zero phase detector 60 and receives setting information on the duty ratio from the setting unit 80 and outputs the PWM charge control signal to the charge switching unit 20 .

At this time, the charge control section 70 receives the charge inhibition signal from the discharge control section 90 at a certain point in time before and after the zero crossing point and does not output the PWM charge control signal, and the charge inhibition signal from the discharge control section 90 The charge switch unit Q1 of the charge switching unit 20 is turned on and off by determining that the discharging of the charger unit 40 has been completed and outputting the PWM charge control signal to the charge switching unit 20. [ At this time, the duty ratio is decreased as the input power is closer to the peak point of the waveform of the input power, and the duty ratio is increased as the input power is farther from the peak point.

When the charging control signal is applied, the charging switch element Q1 is turned on and the input power is applied to the first to third capacitors c1 to c3 through the second to fourth diodes D2 to D4, Thereby charging the capacitors C1 to C3.

During charging, the discharge controller 90 uses the zero crossing point input from the zero phase detector 60 and the voltage value of the output terminal input from the output voltage detector 50 to determine the state of the waveform of the present output voltage If the voltage of the input power source is in a downward trend and the voltage level of the output terminal reaches the discharge reference value set by the setting unit 80, the discharge control unit 30 outputs the discharge control signal to the discharge switching unit 30 The discharging switches S2 to S4 are turned on to discharge the charging power of the capacitors C1 to C3 included in the charger 40 to the output stage so that the voltage of the output stage is increased so that the output voltage of the output stage becomes the set voltage value ). ≪ / RTI >

In the example shown in FIG. 2, the voltage value corresponds to 100 V, which is the discharge reference value, but the discharge control signal is not outputted because the voltage of the input power source is rising from the zero crossing point. However, in the case of reference numeral 320, since the voltage level of the input power source is falling and the voltage value falls to 100 V or less, which is the discharge reference value, as judged from the zero crossing point, the discharge control for discharging the first condenser C1 And outputs a signal to the first discharge switch S2 of the discharge switching unit 30 to turn on the first discharge switch S2.

When the first discharge switch S2 is turned on, the electric power charged in the first condenser C1 is discharged to the output stage, and the waveform of the output voltage rises sharply as shown by reference numeral 201. [ At this time, the discharge control unit 90 outputs a charge inhibition signal to the charge control unit 70 to block the charge control unit 70 from starting charging, and the charge prohibition signal is supplied until the third capacitor C3 is discharged maintain.

On the other hand, when the discharge control unit 90 irradiates the voltage of the output terminal inputted from the output voltage detection unit 50 and the voltage of the output terminal rapidly rises after the discharge of the first capacitor C1, The discharging control signal is output to the second discharging switch S3 connected to the second capacitor C2 to discharge the charging power of the second capacitor C2 to the output terminal by switching on the discharging control signal. When the second capacitor C2 discharges, (See reference numeral 202).

The discharge controller 90 outputs the discharge control signal to the third discharge switch S4 connected to the third capacitor C3 and turns on the third capacitor C3 when the output voltage falls again to the discharge reference value, Discharging the charging power of the third capacitor C3 to the output terminal, and the output voltage rises again when the third capacitor C3 is discharged (reference numeral 203).

On the other hand, after the third capacitor C3 is discharged, the discharge control section 90 stops outputting the charge inhibition signal to the charge control section 70, and the first to third capacitors C1 to C3 are discharged The charging control unit 70 outputs the PWM charging control signal to the charge switching unit 20 and the capacitors C1 to C3 included in the charging unit 40 ).

The discharging control unit 90 sequentially discharges the first to third capacitors C1 to C3 and outputs the discharging voltage to the discharging control units 211, 212, 213 and 221, 222, and 223, the output voltage is supplied to the output terminal.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

10 rectification part 20 charge switching part
30 discharge switching unit 40 charging unit
50 output voltage detecting unit 60 zero phase detecting unit
70 charging control unit 80 setting unit
90 discharge control section

Claims (10)

A rectifying unit for rectifying the inputted AC power and outputting the smoothed DC power to an output terminal;
A charging unit to be charged using power outputted from the rectifying unit;
A discharging switching unit for connecting the charging unit to the output terminal according to a discharge control signal and discharging the power charged in the charging unit to the output terminal to smooth the output voltage of the output terminal; And
And a discharge control unit for outputting the discharge control signal when the voltage of the output terminal falls below a predetermined discharge reference value,
The charging unit includes a plurality of capacitors provided in parallel,
Wherein the discharge switching unit includes a plurality of discharge switches connecting the plurality of capacitors and the output terminal,
Wherein the discharge control signal is output to each of the plurality of discharge switches to sequentially turn on the plurality of discharge switches. delete The method according to claim 1,
A zero phase detector for receiving an AC power input to the rectifier and outputting a zero crossing point; And
And a setting unit for outputting the discharge reference value in accordance with a user's setting,
The discharge control unit is configured to output the discharge control signal when the voltage of the output terminal is lowered by using the zero crossing point input from the zero phase detector and the discharge reference value and the voltage of the output terminal becomes the discharge reference value or less DC converter. The method of claim 3,
The charging unit includes a plurality of capacitors provided in parallel,
Wherein the discharge switching unit includes a plurality of discharge switches connecting the plurality of capacitors and the output terminal,
Wherein the discharge control unit outputs the discharge control signal so that one of the plurality of capacitors is discharged when the voltage of the output terminal becomes equal to or lower than the discharge reference value and when the voltage value increased by the discharged capacitor again falls below the discharge reference value, And the discharge control signal is outputted so that the other one of the plurality of capacitors is discharged, so that the voltage of the output terminal is maintained to be equal to or greater than the discharge reference value. 5. The method of claim 4,
The charging unit
A plurality of diodes whose anode is connected to the rectification part and whose cathode is connected to one end of the capacitor; And
A plurality of capacitors connected to a cathode of the diode and grounded at the other end,
The discharge switching unit
And a plurality of discharge switches each having one end connected to the output terminal and the other end connected to the cathode of the diode and the connection node of the capacitor. The method according to claim 1,
Further comprising an output voltage detector for dividing the voltage of the output terminal and providing the divided voltage to the discharge controller,
Wherein the discharge control unit calculates the magnitude of the voltage at the output terminal using the voltage input from the output voltage detection unit. The method according to claim 1,
Further comprising a charge switching unit for outputting the smoothed direct current power outputted from the rectifying unit to the output terminal and for supplying the direct current power to the charging unit when the charging control signal is inputted to charge the capacitors included in the charging unit DC converter. 8. The apparatus of claim 7, wherein the charge switching unit
An inductor connected to the rectifying part,
A diode connected to the inductor to block a current discharged from the charging unit from flowing to the rectifying unit,
And a charge switch element having one end connected to a node between the inductor and the diode and the other end connected to one or more capacitors included in the charging part. 8. The method of claim 7,
A zero phase detector for receiving an AC power input to the rectifier and outputting a zero crossing point;
Further comprising a charge controller for receiving a zero crossing point from the zero phase detector, receiving a duty ratio reference value from the setting unit, and outputting the charge control signal implemented as a PWM signal to the charge switching unit to charge the charge unit,
Wherein the charge control unit outputs the charge control signal by setting a duty ratio to be closer to a zero crossing point and a duty ratio to be closer to a peak value of the input power source to be smaller. 10. The method of claim 9,
The discharge control unit outputs a charge inhibition signal to the charge control unit while discharging the charging unit,
Wherein the charge control unit does not output the charge control signal to the charge switching unit while the charge inhibition signal is being input.

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