KR20170015843A - Power Supply Device and Display Device using the same - Google Patents

Abstract

The present invention relates to a power supply unit and a display device using the same, which solves a problem of efficiency loss and efficiency degradation due to switching, overcomes limitation of output voltage variable time, and is capable of rapid voltage variation by controlling simple bidirectional power transfer (bidirectional power transfer by duty variation). The power supply unit has a first DC power conversion unit and a second DC power conversion unit. The second DC power conversion unit is connected to the first DC power conversion unit in the form of a parallel stage capable of bidirectional power transfer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply unit,

The present invention relates to a power supply unit and a display device using the same.

As the information technology is developed, the market of display devices, which is a connection medium between users and information, is getting larger. Accordingly, the organic light emitting diode (OLED), the quantum dot display (QDD), the liquid crystal display (LCD), the plasma display panel (PDP) The use of the same display device is increasing.

Some of the above-described display devices, for example, a liquid crystal display device and an organic electroluminescent display device are provided with a display panel including a plurality of sub-pixels arranged in a matrix form, a driver for outputting a drive signal for driving the display panel, A power supply unit for generating a power supply to be supplied, and the like.

 The driving unit includes a scan driver for supplying a scan signal (or a gate signal) to the display panel, and a data driver for supplying a data signal to the display panel. When a driving signal, such as a scan signal and a data signal, is supplied to the subpixels formed on the display panel, the selected subpixel emits light so that an image can be displayed.

Some of the above-described display devices include an LLC half bridge DC-DC converter (DC-DC converter) having a fixed output voltage and a synchronous buck converter The display device is implemented based on the power supply unit. However, the power supply unit as described above has a problem in that efficiency (loss of efficiency) of the entire system is lowered, and improvement thereof is required.

The present invention has been made to solve the problems of the background art described above, and it is an object of the present invention to solve the problem of efficiency loss and efficiency reduction due to switching, to overcome the limit of the output voltage variable time and to perform simple bidirectional current transportation control And a display device using the power supply unit.

According to an aspect of the present invention, there is provided a power supply unit including a first DC power conversion unit and a second DC power conversion unit. The first DC power converting unit has a main transformer for converting the first DC voltage supplied from the outside and outputting it as a second DC voltage. The second direct-current power conversion unit has a pump transformer for converting the second direct-current voltage and outputting it as a third direct-current voltage. The second direct current power conversion unit is connected to the first direct current power conversion unit in the form of a parallel stage capable of bi-directional power transfer.

The primary winding side of the pump transformer may be connected to the secondary winding side of the main transformer in the form of a parallel stage.

The first direct current power conversion section includes an output capacitor located at a high potential output line, the second direct current power conversion section includes a tank capacitor located at a second secondary winding side of the pump transformer, And pump switches for bi-directional power transfer between the capacitor and the tank capacitor.

Pump switches can be Zero Voltage Switching (ZVS) only in the voltage balanced state.

As the duty of at least one of the pump switches increases, the output voltage across the high-voltage output line of the first DC power conversion section decreases with the voltage charge of the tank capacitor, and when the duty of at least one of the pump switches decreases, The voltage discharge can increase the output voltage through the high-potential voltage output line of the first DC power converting portion.

A main control unit for changing a switching frequency of the first DC power source conversion unit and a power control unit having a pump control unit for outputting a voltage change signal for controlling a variable speed of the second DC power source unit and varying a switching frequency of the first DC power source conversion unit, As shown in FIG.

The second DC power source conversion section is connected to the first terminal on the first secondary winding side of the main transformer and to the fifth terminal on the secondary winding side of the main transformer and to the low potential voltage output line of the first DC power source conversion section, A pump diode having an anode electrode connected to the fourth terminal on the second secondary winding side of the pump transformer and having a cathode electrode connected to the tank capacitor, and a pump diode having one end connected to the cathode electrode of the pump diode, A pump capacitor having one end connected to the high potential voltage output line of the first direct current power converting unit and the other end connected to the third terminal on the second winding side of the pump transformer, A gate electrode is connected to a first output terminal of the pump control unit, a first electrode is connected to the other end of the pump inductor, a low potential voltage output line of the first DC power conversion unit, A gate electrode is connected to a second output terminal of the pump control unit, a first electrode is connected to the other end of the pump inductor, a cathode electrode of the pump diode is connected to a second electrode of the pump diode, And a second pump switch having a second electrode connected to one end of the tank capacitor.

And a bridge switch located between the output of the first direct current power source conversion unit and the input of the second direct current power source conversion unit, wherein the bridge switch is electrically connected between the first direct current power source conversion unit and the second direct current power source conversion unit Can be turned off for isolation.

Further comprising a bridge switch having a first electrode connected to one end of the pump inductor and a second electrode connected to a high potential output line of the first DC power conversion unit and a control electrode connected to the pump control unit, And may be turned on or off in response to the applied bridge switch control signal.

The pump control unit supplies a reference voltage for changing the switching frequency of the first DC power source conversion unit to the main control unit. When the output voltage of the first DC power source conversion unit is variable, a voltage having a minus exponential function form or a minus exponential function The reference voltage can be changed by a step voltage having a stepped shape.

In another aspect, the present invention provides a display device including a display panel and a power supply portion. The display panel displays the image. The power supply unit outputs power necessary for the apparatus driving the display panel. The power supply unit includes a first DC power conversion unit and a second DC power conversion unit. The first DC power converting unit has a main transformer for converting the first DC voltage supplied from the outside and outputting it as a second DC voltage. The second direct-current power conversion unit has a pump transformer for converting the second direct-current voltage and outputting it as a third direct-current voltage. The second direct current power conversion unit is connected to the first direct current power conversion unit in the form of a parallel stage capable of bi-directional power transfer.

The first direct current power conversion section includes an output capacitor located at a high potential output line, the second direct current power conversion section includes a tank capacitor located at a second secondary winding side of the pump transformer, And pump switches for bi-directional power transfer between the capacitor and the tank capacitor.

As the duty of at least one of the pump switches increases, the output voltage across the high-voltage output line of the first DC power conversion section decreases with the voltage charge of the tank capacitor, and when the duty of at least one of the pump switches decreases, The voltage discharge can increase the output voltage through the high-potential voltage output line of the first DC power converting portion.

A main control unit for changing a switching frequency of the first DC power source conversion unit and a power control unit having a pump control unit for outputting a voltage change signal for controlling a variable speed of the second DC power source unit and varying a switching frequency of the first DC power source conversion unit, As shown in FIG.

The second DC power source conversion section is connected to the first terminal on the first secondary winding side of the main transformer and to the fifth terminal on the secondary winding side of the main transformer and to the low potential voltage output line of the first DC power source conversion section, A pump diode having an anode electrode connected to the fourth terminal on the second secondary winding side of the pump transformer and having a cathode electrode connected to the tank capacitor, and a pump diode having one end connected to the cathode electrode of the pump diode, A pump capacitor having one end connected to the high potential voltage output line of the first direct current power converting unit and the other end connected to the third terminal on the second winding side of the pump transformer, A gate electrode is connected to a first output terminal of the pump control unit, a first electrode is connected to the other end of the pump inductor, a low potential voltage output line of the first DC power conversion unit, A gate electrode is connected to a second output terminal of the pump control unit, a first electrode is connected to the other end of the pump inductor, a cathode electrode of the pump diode is connected to a second electrode of the pump diode, And a second pump switch having a second electrode connected to one end of the tank capacitor.

And a bridge switch located between the output of the first direct current power source conversion unit and the input of the second direct current power source conversion unit, wherein the bridge switch is electrically connected between the first direct current power source conversion unit and the second direct current power source conversion unit Can be turned off for isolation.

Further comprising a bridge switch having a first electrode connected to one end of the pump inductor and a second electrode connected to a high potential output line of the first DC power conversion unit and a control electrode connected to the pump control unit, And may be turned on or off in response to the applied bridge switch control signal.

The pump control unit supplies a reference voltage for changing the switching frequency of the first DC power source conversion unit to the main control unit. When the output voltage of the first DC power source conversion unit is variable, a voltage having a minus exponential function form or a minus exponential function The reference voltage can be changed by a step voltage having a stepped shape.

The present invention solves the problem of efficiency degradation because the pump switches operate only at the moment when the output voltage is varied and there is no power consumed in the voltage balanced state. In addition, since the hard switching period is very short, the efficiency loss due to switching can be reduced. Further, the present invention can overcome the limit of variable output time of the output voltage and can perform simple bidirectional current transport control (bi-directional power transfer by duty change). In addition, the present invention enables rapid voltage fluctuation while preventing efficiency loss of the output stage by varying the feedback signal and the switching duty ratio. In addition, since the present invention has the above-described driving characteristics and performance, it is possible to exhibit even greater effects when applied to a display device which requires a high potential voltage to change quickly. Further, the present invention has the effect of maintaining a quick voltage variable and stable output. In addition, the present invention has an effect that the reference voltage is varied in the form of a specific function for fast and stable voltage variation, and the parasitic resonance between them is eliminated or improved by electrically separating the pump circuit and the main circuit from each other only in the voltage balanced state .

1 is a block diagram schematically showing a display device;
Fig. 2 is a schematic view showing the subpixel shown in Fig. 1. Fig.
FIG. 3 is a block diagram for helping a schematic understanding of a power supply unit according to an experimental example. FIG.
4 is a waveform diagram for explaining efficiency loss due to the switching operation of the synchronous buck converter added to the experimental example.
5 is a block diagram for helping a schematic understanding of a power supply unit according to the first embodiment;
6 is a waveform diagram for explaining efficiency improvement according to the switching operation of the circuit portion added to the first embodiment;
7 is a waveform diagram for explaining a bidirectional power transmission system according to the operation of the circuit portion added to the first embodiment;
8 is a circuit configuration diagram showing a part of a power supply unit according to the first embodiment;
9 is a circuit configuration diagram showing a part of the power control section;
10 and 11 are circuit diagrams for explaining the operation of the power supply unit according to the first embodiment.
12 is a waveform diagram showing the relationship between the switch operation of the third power conversion section and the reference voltage.
13 and 14 are waveform diagrams for explaining a driving characteristic of a power supply part when a voltage is changed in a full load state.
15 and 16 are waveform diagrams for explaining the driving characteristics of the power supply unit when the voltage is lowered and the voltage is increased.
17 is a circuit diagram showing a part of a power supply unit according to the second embodiment;
18 is a block diagram briefly explaining an improvement in the output voltage varying operation of the power supply unit according to the first embodiment;
19 is a circuit configuration diagram showing a part of a power supply control unit according to the second embodiment;
20 is a waveform diagram showing the difference between the first and second embodiments;
FIGS. 21 and 22 illustrate exemplary variable voltage waveforms of reference voltages for reducing RC delay according to the second embodiment. FIG.
23 and 24 are waveform diagrams for comparing and explaining main control features of the power supply unit according to the first embodiment and the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The display device according to the present invention is implemented as a television, a set-top box, a navigation device, a video player, a Blu-ray player, a personal computer (PC), a home theater and a mobile phone. The display panel of the display device may be a liquid crystal display panel, an organic light emitting display panel, an electrophoretic display panel, a plasma display panel, or the like, but is not limited thereto. In the following description, an organic electroluminescent display device will be described as an example for convenience of explanation.

Fig. 1 is a block diagram schematically showing a display device, and Fig. 2 is a schematic diagram showing a subpixel shown in Fig.

1, the display device includes an image supply unit 110, a timing control unit 120, a scan driving unit 130, a data driving unit 140, a display panel 150, and a power supply unit 180.

The image supply unit 110 processes the data signal and outputs the image signal together with a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a clock signal. The image supply unit 110 supplies a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, a clock signal, and a data signal to the timing controller 120 (LVDS) through an LVDS (Low Voltage Differential Signaling) interface or a TMDS (Transition Minimized Differential Signaling) .

The timing controller 120 receives a data signal DATA from the image supplier 110 and receives a gate timing control signal GDC for controlling the operation timing of the scan driver 130 and an operation timing of the data driver 140 And outputs a data timing control signal (DDC)

The timing controller 120 outputs the data signal DATA together with the gate timing control signal GDC and the data timing control signal DDC through the communication interface and outputs the data signal DATA to the scan driver 130 and the data driver 140 .

The scan driver 130 outputs a gate voltage of a logic high as a scan signal (or a gate signal) in response to a gate timing control signal GDC supplied from the timing controller 120. The scan driver 130 includes a level shifter and a shift register.

The scan driver 130 supplies the scan signals to the sub-pixels SP included in the display panel 150 through the scan lines GL1 to GLm. The scan driver 130 is formed in the form of an integrated circuit (IC) or a gate-in-panel type display panel 150. The portion of the scan driver 130 formed in a gate-in-panel manner is a shift register.

The data driver 140 samples and latches the data signal DATA in response to the data timing control signal DDC supplied from the timing controller 120 and converts the digital signal into an analog signal corresponding to the gamma reference voltage and outputs the analog signal .

The data driver 140 supplies the data signal DATA to the sub-pixels SP included in the display panel 150 through the data lines DL1 to DLn. The data driver 140 is formed in the form of an integrated circuit (IC).

The power supply unit 180 generates and outputs voltages Vout and GND based on voltages supplied from the outside. The high-potential voltage Vout and the low-potential voltage GND output from the power supply unit 180 are used in various apparatuses included in the display apparatus. For example, the high-potential voltage Vout and the low-potential voltage GND output from the power supply unit 180 may be supplied to the display panel 150. [

The display panel 150 displays an image corresponding to the scan signal supplied from the scan driver 130 and the data signal DATA supplied from the data driver 140. The display panel 150 includes sub-pixels SP.

As shown in FIG. 2, one subpixel is supplied through a switching thin film transistor SW and a switching thin film transistor SW which are connected (or formed at intersections) to a scan line GL1 and a data line DL1 And a pixel circuit PC that operates in response to the data signal DATA. The subpixels SP consist of a liquid crystal display panel including a liquid crystal element according to the configuration of the pixel circuit PC or an organic light emitting display panel including an organic light emitting element.

When the display panel 150 is composed of a liquid crystal display panel, it may be a twisted nematic (TN) mode, a VA (Vertical Alignment) mode, an IPS (In Plane Switching) mode, a FFS (Fringe Field Switching) mode, or an ECB (Electrically Controlled Birefringence) Mode. When the display panel 150 is formed of an organic light emitting display panel, the display panel 150 may be implemented as a top emission type, a bottom emission type, or a dual emission type.

The display device includes the display panel 150 based on the voltages Vout and GND output from the power supply unit 180 and the scan signals and the data signals DATA output from the scan driver 130 and the data driver 140, As the light is emitted or transmitted, a specific image is displayed.

Some of the display devices include an LLC half bridge DC-DC converter having an output voltage fixed and a synchronous buck converter capable of varying an output voltage. The display device is implemented based on the power supply unit.

However, the power supply unit as described above has a problem in that efficiency (loss of efficiency) of the entire system is lowered, and improvement thereof is required.

Hereinafter, a problem of the power supply unit according to an experimental example will be discussed, and an embodiment derived to solve the problem will be described.

- Experimental Example -

FIG. 3 is a block diagram for helping a schematic understanding of a power supply unit according to an experimental example, and FIG. 4 is a waveform diagram for illustrating efficiency loss due to a switching operation of a synchronous buck converter added to an experimental example.

3 and 4, the power supply unit according to the experimental example includes a first power conversion unit 180a, a second power conversion unit 180b, and a third power conversion unit 180c. The power supply unit converts the AC voltage AC supplied from the outside to the DC voltage DC based on the first power conversion unit 180a, the second power conversion unit 180b, and the third power conversion unit 180c Output.

The first power conversion unit 180a converts an AC voltage supplied from the outside into a DC voltage and outputs the DC voltage. The first power conversion unit 180a converts the AC voltage into a first DC voltage (for example, DC 390V) corresponding to a high voltage and outputs the first DC voltage. The first power conversion unit 180a may include a power conversion unit, a power factor correction (PFC), and an electromagnetic wave shielding unit.

The second power conversion unit 180b functions to step down the first DC voltage output from the first power conversion unit 180a and output the first DC voltage. The second power conversion section 180b converts the first DC voltage into a second DC voltage (e.g. DC 22V) and outputs it. The second power conversion unit 180b may include a switch, an inductor, an output capacitor, and a transformer. The second power conversion unit 180b is implemented as an LLC half bridge DC-DC converter.

The third power converter 180c varies the second DC voltage output from the second power converter 180b and outputs the second DC voltage as a third DC voltage. The third power source conversion section 180c varies the level of the second DC voltage to convert it into a third DC voltage (for example, DC 16-20V) and outputs it. The third power conversion unit 180c may include a switch, an inductor, an output capacitor, and the like. The third power conversion unit 180c is implemented in the form of a synchronous buck converter.

In the power supply unit according to the experimental example, the first power source conversion unit 180a, the second power source conversion unit 180b, and the third power source conversion unit 180c constituting the system are connected in the form of a serial stage. As a result of measuring the efficiency of the entire system of the power supply unit according to the experimental example, there is a problem that the loss increases. In the case of the power supply unit according to the experimental example, before the third power conversion unit 180c was added, efficiency of the system as a whole was 80% or more. However, after the third power conversion unit 180c was added, the efficiency was 80% or less.

The analysis result of the reason why the power supply unit according to the experimental example causes the above efficiency loss will be described as follows.

The power supply according to the experimental example is a serial power transmission structure. Therefore, efficiency loss is accompanied by the step of adding the overall system efficiency through the first power source conversion unit 180a, the PFC, the second power source conversion unit 180b, and the third power source conversion unit 180c.

In the power supply unit according to the experimental example, system efficiency is degraded by hard switching. The third power conversion unit 180c performs hard switching while the switch is on / off. Hard switching causes the voltage and current to flow in the switch during a transient period during which the switch is on / off, releasing energy in a thermal fashion. Therefore, hard switching shortens the lifetime of the switch element, which in turn reduces the efficiency of the entire system.

The power supply unit according to the experimental example has a limit of variable output voltage time. The output voltage variable using the third power conversion unit 180c is a method of changing the feedback signal to a desired target voltage. Since the voltage change time required when changing the target voltage of the third power conversion unit 180c is determined by the capacity of the output capacitor and the output load rather than the performance of the third power conversion unit 180c, . (At this time, the output capacitance is large irrespective of the performance of the third power conversion unit 180c, and the voltage change time becomes longer as the output resistance becomes larger.)

The power supply unit according to the experimental example is implemented as a complex type bidirectional converter. In addition to the experimental example, the bidirectional converter used in the conventional power supply unit requires a control device capable of controlling four switches in each mode. In addition, a complicated feedback structure for output voltage and switch control is required for each mode.

Therefore, although the power supply unit according to the experimental example has an advantage that the output voltage can be varied, there is a problem that efficiency (loss of efficiency) of the entire system is lowered due to various causes (problems such as addition of the synchronous buck converter) And improvement thereof is required.

- First Embodiment -

FIG. 5 is a block diagram for helping a schematic understanding of the power supply unit according to the first embodiment, FIG. 6 is a waveform chart for explaining efficiency improvement according to the switching operation of the circuit unit added to the first embodiment, FIG. Is a waveform diagram for explaining a bidirectional power transmission system according to the operation of the circuit portion added to the first embodiment.

5 to 7, the power supply unit according to the first embodiment includes a first power conversion unit 180a, a second power conversion unit 180b, and a third power conversion unit 180c. The power supply unit converts the AC voltage AC supplied from the outside to the DC voltage DC based on the first power conversion unit 180a, the second power conversion unit 180b, and the third power conversion unit 180c Output.

The first power conversion unit 180a converts an AC voltage supplied from the outside into a DC voltage and outputs the DC voltage. The first power conversion unit 180a converts the AC voltage into a first DC voltage (for example, DC 390V) corresponding to a high voltage and outputs the first DC voltage. The first power conversion unit 180a may include a power conversion unit, a power factor correction (PFC), and an electromagnetic wave shielding unit. The first power conversion unit 180a may be defined as an AC-DC conversion unit that converts AC into DC.

The second power conversion unit 180b functions to step down the first DC voltage output from the first power conversion unit 180a and output the first DC voltage. The second power conversion section 180b converts the first DC voltage into a second DC voltage (e.g. DC 22V) and outputs it. The second power conversion unit 180b may include a switch, an inductor, an output capacitor (output Cap.), And a transformer (transformer). The second power conversion unit 180b is implemented as an LLC half bridge DC-DC converter. And the second power conversion unit 180b may be defined as a first DC power conversion unit.

The third power conversion unit 180c varies the second DC voltage output from the second power conversion unit 180b and outputs the second DC voltage. The third power source conversion section 180c varies the level of the second DC voltage to convert it into a third DC voltage (for example, DC 16-20V) and outputs it. The third power conversion unit 180c may include a switch, an inductor, a transformer (transformer), and a tank capacitor (or an energy tank).

The third power conversion unit 180c is implemented in the form of a two-switch pump converter having a ZVS (Zero Voltage Switching) switch or the like in the voltage balance period. And the third power conversion unit 180c may be defined as a second DC power conversion unit.

The capacity (Cap1) of the output capacitor and the capacity (Cap2) of the tank capacitor may have a relationship of Cap1 < Cap2. The capacity of the tank capacitor may be larger than the capacity of the output capacitor. The capacity of the tank capacitor can be such that it can cover the voltage that is applied to the peak.

In the power supply unit according to the first embodiment, the first power conversion unit 180a and the second power conversion unit 180b constituting the system are connected in the form of a serial stage. On the other hand, the third power conversion unit 180c is connected to the second power conversion unit 180b in the form of a parallel stage capable of bi-directional power transfer. Specifically, the power supply unit according to the first embodiment can transmit bi-directional power between the output capacitor (output Cap) of the second power conversion unit 180b and the tank capacitor (Energy Tank) of the third power conversion unit 180c And the pump switches of the third power conversion unit 180c are connected in parallel so that current can be quickly transmitted and received.

As a result of measuring the efficiency of the entire power supply unit according to the first embodiment, it is found that there is power consumed to vary the output voltage of the pump switches, and there is no power consumed in the voltage balanced state, It can be solved. In the case of the power supply unit according to the first embodiment, even after the third power conversion unit 180c is added, the efficiency of the system as a whole is more than 80%.

The power supply unit according to the first embodiment is a result of improving the system efficiency by soft switching (Sofe Switching) as opposed to the experimental example. 6 (a)). However, the pump switches of the third power conversion unit 180c perform ZVS (FIG. 6 (b)) only in the voltage balanced state . The pump switches of the third power conversion unit 180c are hard switched only in the operation in which the output voltage is variable. Therefore, the pump switch converter of the first embodiment is very advantageous in terms of reducing the efficiency loss due to the switching because the hard switching period is short compared to the synchronous buck converter of the experimental example.

The power supply unit according to the first embodiment can overcome the limit of the output voltage variable time and can perform simple bidirectional current transportation control (bidirectional power transfer by duty change). Since the power supply unit according to the first embodiment carries the current between the LLC output capacitor of the second power supply conversion unit 180b and the energy capacitor of the third power supply conversion unit 180c, And the ability of the pump switches of the power conversion section 180c.

The current transfer by the pump switches of the third power source conversion unit 180c is determined by the duty ratio of the switch (Boost switch) of the third power source conversion unit 180c. The waveform shown in FIG. 7 is a waveform for understanding the operation of the pump switches of the third power conversion unit 180c.

7, the LLC output voltage of the second power conversion unit 180b is fixed (unchanged, constantly maintained at 16V) for understanding the operation of the pump switches of the third power conversion unit 180c And the duty ratio of the pump switches of the third power converter 180c is varied.

The first waveform is the LLC output voltage of the second power conversion section 180b. (LLC has a fixed output of 16V). And the second waveform is a current waveform that is transferred to the pump switches of the third power conversion unit 180c. And the third waveform is the voltage waveform of the tank capacitor of the third power conversion unit 180c.

1) LLC Output Capacitor (Output Cap) → Power Transfer to Tank Capacitor (Energy Tank)

The duty of the switch of the third power conversion unit 180c is increased from 0.5 to 0.7.

As a result, current transport occurs from the LLC output capacitor (output Cap) to the tank capacitor (Energy Tank). (See waveforms in which the current drawn by the pump switches falls below zero)

When an instantaneous drop in LLC output voltage occurs, the voltage on the energy tank increases.

When the LLC is controlled so that the LLC output voltage is maintained at the changed value after the instantaneous voltage fluctuation, the level of the output voltage is also transferred to the second power conversion unit 180b. (Control to increase LLC switching frequency)

 2) Transfer the power from the Tank Capacitor (Energy Tank) to the LLC Output Capacitor (Output Cap)

The duty of the switch of the third power conversion unit 180c is reduced to 0.7 -> 0.5.

As a result, current transfer occurs from the tank capacitor (Energy Tank) to the LLC output capacitor (Output Cap). (See waveforms in which the current to pump switches goes up to zero)

When the LLC output voltage rises momentarily, the voltage of the energy tank falls.

When the LLC is controlled so that the LLC output voltage is maintained at the changed value after the instantaneous voltage fluctuation, the level of the output voltage is also transferred to the second power conversion unit 180b. (Control to reduce the LLC switching frequency)

With such driving characteristics, when the duty of the switch of the third power source conversion section 180c increases, the output decreases due to the charging of the tank capacitor (Energy Tank). When the duty of the switch of the third power conversion unit 180c decreases, the output increases due to the discharge of the tank capacitor (Energy Tank).

The circuit configuration of the power supply unit according to the first embodiment and its operation will be described below.

FIG. 8 is a circuit configuration diagram showing a part of the power supply unit according to the first embodiment, FIG. 9 is a circuit configuration diagram showing a part of the power supply control unit, FIGS. 10 and 11 are views And FIG. 12 is a waveform diagram showing the relationship between the switch operation of the third power conversion unit and the reference voltage.

8 and 9, the power supply unit according to the first embodiment includes a second power converter (LLC, a main converter (Half Bridge), a third power converter (Pump), a pump converter (Boost) And a power control unit (CNT). In the power supply unit according to the first embodiment, the third power source conversion unit (Pump) is connected to the second power source conversion unit (LLC) in the form of a parallel stage.

The second power conversion unit LLC includes main switches ST1 and ST2, a main inductor LL, a main capacitor CL, a main transformer TRS1, main diodes DL1 and DL2, an output capacitor CO, And an output resistor RL.

The third power conversion unit Pump includes a pump transformer TRS2, pump switches BT1 and BT2, a pump inductor LP, a pump diode DP and a tank capacitor CP.

The power control unit CNT includes a main control unit HBC for changing the switching frequency of the second power conversion unit LLC and a pump control unit MCU for adjusting the variable speed of the third power conversion unit Pump .

The first main switch ST1 has a gate electrode connected to the first output terminal of the main control unit HBC, a first electrode connected to the first voltage terminal (+) of the input voltage terminal VIN, The second electrode is connected to one end of the second electrode. The first main switch ST1 is turned on or off by the first main switch signal output through the first output terminal of the main control unit HBC.

The second main switch ST2 has a gate electrode connected to a second output terminal of the main control unit HBC, a first electrode connected to a second voltage terminal (-) of the input voltage terminal VIN, and a main inductor LL The second electrode is connected to one end of the second electrode. The second main switch ST2 is turned on or off by the second main switch signal output through the second output terminal of the main control unit HBC.

The main inductor LL has one end connected to the second electrode of the first main switch ST1 and the second main switch ST2 and the other end connected to the first terminal W1 on the first main winding side of the main transformer TRS1 Lt; / RTI >

The main capacitor CL is connected at one end to the second voltage terminal (-) of the input voltage terminal VIN and at the first electrode of the second main switch ST2 and at one end of the main transformer TRS1 And the other end is connected to the third terminal W3.

The main transformer TRS1 has a first terminal W1 on the first winding side connected to the other terminal of the main inductor LL and a third terminal W3 on the first winding side on the other terminal of the main capacitor CL. Respectively. The main transformer TRS1 is connected to an anode electrode of the first main diode DL1 and a fourth terminal W4 of the second main winding DL2 and to an anode electrode of the second main diode DL2, Is connected to the sixth terminal W6.

The main transformer TRS1 has the first terminal W1 to the third terminal W3 on the first winding side and the fourth terminal W4 to the sixth terminal W6 on the second winding side . The second terminal W2 on the first main winding side and the fourth terminal W4 on the second main winding side are located at positions opposite to the first terminal W1 on the first main winding side of the main transformer TRS1, And a sixth terminal W6 on the second secondary winding side is provided at a position facing the third terminal W3 on the first primary winding side have.

The first main diode DL1 is connected to an anode electrode of the main transformer TRS1 on the second winding side and a fourth terminal W4 of the main transformer TRS1 on the high potential output line Vout of the second power conversion unit LLC The cathode electrode is connected.

The second main diode DL2 is connected to the anode terminal of the sixth terminal W6 of the main transformer TRS1 on the second winding side and the anode electrode of the second main power supply line LLC is connected to the high potential output line Vout of the second power conversion unit LLC The cathode electrode is connected.

The output capacitor CO is connected at one end to the high potential voltage output line Vout of the second power conversion unit LLC and at the other end to the low potential voltage output line GND.

The output resistor RL is connected at one end to the high-potential voltage output line Vout of the second power conversion unit LLC and at the other end to the low-potential voltage output line GND.

The second power converter LLC controls the switching frequency at which the main switches ST1 and ST2 are turned on or off in response to the first and second main switch signals output from the main controller HBC The first DC voltage input through the input voltage terminal VIN is stepped down to be converted into a second DC voltage and output.

The pump transformer TRS2 is connected in parallel to the fifth terminal W5 on the secondary winding side of the main transformer TRS1. The pump transformer TRS2 is connected between the first terminal W1 of the first primary winding and the fifth terminal W5 of the main transformer TRS1 on the secondary winding side of the main transformer TRS1, And the second terminal W2 on the first winding side is connected to the potential voltage output line GND. The pump transformer TRS2 is connected to the low potential voltage output line GND and the first electrode of the first pump switch BT1 to the third terminal W3 of the secondary winding side, The fourth terminal W4 on the secondary winding side is connected to the anode electrode of the secondary winding.

The pump transformer TRS2 has the first terminal W1 and the second terminal W2 on the first winding side and the third terminal W3 and the fourth terminal W4 on the second winding side . The third terminal W3 on the second secondary winding side is located at a position facing the first terminal W1 on the first primary winding side of the pump transformer TRS2 and the second terminal W2 on the secondary side of the first transformer TRS2, And the fourth terminal W4 on the side of the secondary winding.

The anode of the pump diode DP is connected to the fourth terminal W4 of the pump transformer TRS2 on the second winding side and the anode electrode of the pump diode TRS2 is connected to one end of the tank capacitor CP and the second electrode of the second pump switch BT2 The cathode electrode is connected.

The tank capacitor CP is connected at one end to the cathode electrode of the pump diode DP and to the second electrode of the second pump switch BT2 and is connected to the low potential voltage output line GND and the secondary winding of the pump transformer TRS2 And the other end is connected to the third terminal W3.

The first pump switch BT1 has a gate electrode connected to the first output terminal of the pump control unit MCU, a first electrode connected to the other end of the pump inductor LP and a low potential voltage output line GND and a pump transformer The second electrode is connected to the third terminal W3 on the second winding side of the second winding TRS2. The first pump switch BT1 is turned on or off by the first pump switch signal outputted through the first output terminal of the pump control unit MCU.

The second pump switch BT2 has a gate electrode connected to the second output terminal of the pump control unit MCU and a first electrode connected to the other end of the pump inductor LP and connected to the cathode electrode of the pump diode DP and the tank capacitor CP is connected to one end of the second electrode. The second pump switch BT2 is turned on or off by the second pump switch signal outputted through the second output terminal of the pump control unit MCU.

The pump inductor LP is connected at one end to the high potential output line Vout of the second power conversion unit LLC and the other end is connected to the first electrode of the first pump switch BT1 and the second pump switch BT2 .

The main control unit HBC outputs main switch signals STC for turning on or off the main switches ST1 and ST2. The pump control unit (MCU) outputs pump switch signals (SWC) for controlling the pump switches (BT1, BT2) to be turned on or off. The main control unit (HBC) and the pump control unit (MCU) are connected via a voltage change line.

In the main control unit HBC, the voltage value of the internal reference voltage Vref is varied by the voltage change signal provided from the pump control unit MCU. The frequency of the main switch signals STC output from the main control unit HBC also changes if the voltage value of the reference voltage Vref is varied by the voltage change signal provided from the pump control unit MCU.

The main control unit HBC includes a voltage sensing unit FEA and a signal generating unit PWM. The voltage sensing unit FEA may be referred to as a feedback error amplifier circuit (Feedback Error Amplifier). The voltage sensing unit FEA outputs the feedback signal FB based on the high potential voltage Vout and the reference voltage Vref. The form of the feedback signal FB output from the voltage sensing unit FEA is varied corresponding to the reference voltage Vref. The signal generating unit PWM generates the main switch signals STC in response to the feedback signal FB output from the voltage sensing unit FEA.

As described above, the signal generator PWM of the main controller HBC controls the switching frequency of the main switches ST1 and ST2 in response to the feedback signal FB transmitted through the output terminal of the voltage sensing unit FEA. The frequency of the main switch signals STC is varied. That is, the voltage conversion capability of the second power conversion unit LLC is related to the frequency of the main switch signals STC, and the factors that determine the voltage conversion capability are the high potential Vout and the reference voltage Vref.

The power supply unit according to the first embodiment includes pump switches capable of transmitting bi-directional power between the output capacitor CO of the second power source conversion unit LLC and the tank capacitor CP of the third power source conversion unit Pump in parallel It is connected and can exchange current quickly.

In the power supply unit according to the first embodiment, the second power conversion unit (LLC) basically performs ZVS. However, the pump switches of the third power converter unit perform ZVS only in the voltage balanced state. That is, the pump switches of the third power converter Pump are hard switched only in the operation in which the output voltage is variable.

The power supply unit according to the first embodiment can overcome the limit of the output voltage variable time and can perform simple bidirectional current transportation control (bidirectional power transfer by duty change). Since the power supply unit according to the first embodiment carries the current between the output capacitor CO of the second power source conversion unit LLC and the tank capacitor CP of the third power source conversion unit Pump, 3 power converter (pump).

As shown in FIGS. 10, 11 and 12, the pump switches BT1 and BT2 of the third power conversion unit Pump are provided with switching characteristics of a section in which the output voltage of the power supply unit is not variable, The switching characteristics during the period are different.

- when the output voltage of the power supply is not variable -

During a period in which the output voltage of the power supply unit is not variable, the pump switches BT1 and BT2 of the third power converter Pump are alternately turned on and off with a duty ratio for maintaining the previous state. At this time, the voltage change signal provided from the pump control unit (MCU) to the main control unit (HBC) is configured to maintain V2.

In the equilibrium period in which the output voltage is not variable, the duty ratios of BT1 and BT2 are fixed as the duty ratio of the voltage variable instantaneously changed. In other words, since the operation of the pump switches BT1 and BT2 of the third power converter Pump occurs at the moment when the duty ratio is changed, a certain amount of duty ratio is changed only when the desired output voltage is discriminated and the voltage balance state Lt; / RTI > (Keep the duty ratio changed when the output voltage is not variable)

- When varying the output voltage of power supply -

During a period in which the output voltage of the power supply unit is varied, the pump switches BT1 and BT2 of the third power converter Pump are alternately turned on and off with different duty ratios. The turn-on duty ratio of the first pump switch BT1 is higher than the turn-on duty ratio of the second pump switch BT2, as shown at t1b and t2b in Fig. At this time, the voltage change signal provided from the pump control unit (MCU) to the main control unit (HBC) is changed so that V1 lower than V2 is maintained. When the turn-on duty ratio of the first pump switch BT1 is increased, the turn-on duty ratio of the second pump switch BT2 decreases by the increased turn-on duty ratio of the first pump switch BT1.

When the duty of the first pump switch BT1 increases when the pump operation is performed, the duty ratio of the second pump switch BT2 decreases by an increased ratio. At this time, the turn-on duty ratio of the second power source conversion unit (LLC) is always 50:50. (LLC controls the switching frequency)

In the case of the power supply unit according to the first embodiment, an initial voltage is applied to the tank capacitor CP of the third power supply conversion unit Pump through the main transformer TRS1 of the second power supply conversion unit LLC. In the initial operation of the power supply unit of the first embodiment, the output of the second power conversion unit LLC is applied to the tank capacitor CP by the operation of the pump switches of the third power supply conversion unit Pump. Therefore, the problem of surge voltage or overcurrent flowing into the tank capacitor (CP) during the initial operation of the power supply is prevented (advantageous by the parallel connection structure of the transformer).

In addition, in the case of the power supply unit according to the first embodiment, the voltage variation signal can be fed back together with the output voltage. As a result, in the power supply unit of the first embodiment, when the output voltage varies, the reference voltage Vref of the second power source conversion unit LLC and the switching duty ratio of the third power source conversion unit Pump are varied It is possible to prevent the efficiency loss of the output stage and to perform a rapid voltage fluctuation.

Since the power supply unit according to the first embodiment has the above-described driving characteristics and performance, it can exhibit even greater effects when applied to a display device that needs to rapidly change the high-potential voltage.

Hereinafter, the driving characteristics of the power supply unit according to the first embodiment will be described based on simulation results.

13 and 14 are waveform diagrams for explaining the driving characteristics of the power supply unit when the voltage is changed in the full load state. 13 and 14 show driving characteristics when the power supply unit according to the first embodiment outputs DC 16V and 20V at the time of voltage change in the full load state.

13 and 14, VDS is a voltage across both ends (drain-source) of the pump switches of the third power conversion section, I_trans_pri indicates a current output through the main transformer of the second power conversion section, And V_ref denotes a reference voltage of the second power conversion unit (a voltage fed back to the second power conversion unit).

13 and 14, when the output voltage of the power supply unit is varied (for example, from 16 V to> 20 V), the pump switches of the third power conversion unit have alternate duty ratios, Off. And the voltage change signal provided from the pump control unit to the main control unit is changed to have V1 lower than V2.

15 and 16 are waveform diagrams for explaining the driving characteristics of the power supply unit when the voltage is lowered and the voltage is increased. 15 and 16 show driving characteristics when the voltage of the power supply unit according to the first embodiment falls from 16V to 20V and when the voltage of the power supply unit rises from 20V to 16V.

15 and 16, V_tank denotes the voltage of the tank capacitor of the third power conversion section, I_pump denotes the current output through the pump switches of the third power conversion section, V_out denotes the power output of the power supply section according to the first embodiment, And V_ref denotes a reference voltage of the second power conversion unit (a voltage fed back to the second power conversion unit).

15 and 16, when the duty ratio of the pump switches of the third power source conversion unit is lowered (D: 0.5 - 0.5 V) in order to vary the output voltage of the power supply unit to be variable (for example, > 0.2). At this time, the reference voltage (V_ref) fed back to the second power conversion unit rises.

Conversely, in order to vary the output voltage of the power supply unit (for example, 20V -> 16V), the duty ratio of the pump switches of the third power conversion unit is increased (D: 0.2 -> 0.5). At this time, the reference voltage (V_ref) fed back to the second power conversion unit is lowered.

Since the power supply unit according to the first embodiment operates only when the pump switches vary the output voltage and there is no power consumed in the voltage balanced state, the efficiency reduction problem can be solved. In addition, since the hard switching period of the power supply unit according to the first embodiment is very short, efficiency loss due to switching can be reduced. Also, the power supply unit according to the first embodiment can overcome the limit of the output voltage variable time and can perform the simple bidirectional current transportation control (bidirectional power transmission by the duty change). In addition, the power supply unit according to the first embodiment is capable of rapidly changing the voltage while preventing loss of efficiency of the output stage due to variation of the feedback signal and the switching duty ratio. In addition, since the power supply unit according to the first embodiment has the above-described driving characteristics and performance, it can exhibit a greater effect when applied to a display device in which a high-potential voltage needs to be quickly changed.

Hereinafter, the power supply unit according to the second embodiment will be described. Since the power supply unit according to the second embodiment has a circuit configuration similar to that of the power supply unit described in the first embodiment, the portions not described below refer to the description of the first embodiment.

- Second Embodiment -

FIG. 17 is a circuit diagram showing a part of the power supply unit according to the second embodiment, FIG. 18 is a block diagram for briefly explaining an improvement in the output voltage varying operation of the power supply unit according to the first embodiment, FIG. 20 is a waveform diagram showing a difference between the first and second embodiments. FIG. 21 and FIG. 22 are waveform diagrams showing a part of the power control unit according to the second embodiment, The variable voltage waveform of the reference voltage is shown.

17, the power supply unit according to the second embodiment includes a second power conversion unit (LLC, a main converter (Half Bridge)), a third power conversion unit (Pump, Booster) (CNT). In the power supply unit according to the second embodiment, the third power source conversion unit (Pump) is connected to the second power source conversion unit (LLC) in the form of a parallel stage.

The second power conversion unit LLC includes main switches ST1 and ST2, a main inductor LL, a main capacitor CL, a main transformer TRS1, main diodes DL1 and DL2, an output capacitor CO, And an output resistor RL. The second power converter (LLC) according to the second embodiment also functions to step down the first DC voltage output from the first power converter as in the first embodiment. Therefore, the second power source conversion unit LLC can also be defined as the first DC power source conversion unit.

The third power conversion unit Pump includes a pump transformer TRS2, pump switches BT1 and BT2, a bridge switch BSW, a pump inductor LP, a pump diode DP and a tank capacitor CP . The third power converter Pump according to the second embodiment also varies the second DC voltage output from the second power converter LLC and outputs the third DC voltage as a third DC voltage. Therefore, the third power conversion unit Pump may also be defined as the second DC power conversion unit.

The power control unit CNT includes a main control unit HBC for changing the switching frequency of the second power conversion unit LLC and a pump control unit MCU for adjusting the variable speed of the third power conversion unit Pump .

The first main switch ST1 has a gate electrode connected to the first output terminal of the main control unit HBC, a first electrode connected to the first voltage terminal (+) of the input voltage terminal VIN, The second electrode is connected to one end of the second electrode. The first main switch ST1 is turned on or off by the first main switch signal output through the first output terminal of the main control unit HBC.

The second main switch ST2 has a gate electrode connected to a second output terminal of the main control unit HBC, a first electrode connected to a second voltage terminal (-) of the input voltage terminal VIN, and a main inductor LL The second electrode is connected to one end of the second electrode. The second main switch ST2 is turned on or off by the second main switch signal output through the second output terminal of the main control unit HBC.

The main inductor LL has one end connected to the second electrode of the first main switch ST1 and the second main switch ST2 and the other end connected to the first terminal W1 on the first main winding side of the main transformer TRS1 Lt; / RTI >

The main capacitor CL is connected at one end to the second voltage terminal (-) of the input voltage terminal VIN and at the first electrode of the second main switch ST2 and at one end of the main transformer TRS1 And the other end is connected to the third terminal W3.

The main transformer TRS1 has a first terminal W1 on the first winding side connected to the other terminal of the main inductor LL and a third terminal W3 on the first winding side on the other terminal of the main capacitor CL. Respectively. The main transformer TRS1 is connected to an anode electrode of the first main diode DL1 and a fourth terminal W4 of the second main winding DL2 and to an anode electrode of the second main diode DL2, Is connected to the sixth terminal W6.

The main transformer TRS1 has the first terminal W1 to the third terminal W3 on the first winding side and the fourth terminal W4 to the sixth terminal W6 on the second winding side . The second terminal W2 on the first main winding side and the fourth terminal W4 on the second main winding side are located at positions opposite to the first terminal W1 on the first main winding side of the main transformer TRS1, And a sixth terminal W6 on the second secondary winding side is provided at a position facing the third terminal W3 on the first primary winding side have.

The first main diode DL1 is connected to an anode electrode of the main transformer TRS1 on the second winding side and a fourth terminal W4 of the main transformer TRS1 on the high potential output line Vout of the second power conversion unit LLC The cathode electrode is connected.

The second main diode DL2 is connected to the anode terminal of the sixth terminal W6 of the main transformer TRS1 on the second winding side and the anode electrode of the second main power supply line LLC is connected to the high potential output line Vout of the second power conversion unit LLC The cathode electrode is connected.

The output capacitor CO is connected at one end to the high potential voltage output line Vout of the second power conversion unit LLC and at the other end to the low potential voltage output line GND.

The output resistor RL is connected at one end to the high-potential voltage output line Vout of the second power conversion unit LLC and at the other end to the low-potential voltage output line GND.

The second power converter LLC controls the switching frequency at which the main switches ST1 and ST2 are turned on or off in response to the first and second main switch signals output from the main controller HBC The first DC voltage input through the input voltage terminal VIN is stepped down to be converted into a second DC voltage and output.

The pump transformer TRS2 is connected in parallel to the fifth terminal W5 on the secondary winding side of the main transformer TRS1. The pump transformer TRS2 is connected between the first terminal W1 of the first primary winding and the fifth terminal W5 of the main transformer TRS1 on the secondary winding side of the main transformer TRS1, And the second terminal W2 on the first winding side is connected to the potential voltage output line GND. The pump transformer TRS2 is connected to the low potential voltage output line GND and the first electrode of the first pump switch BT1 to the third terminal W3 of the secondary winding side, The fourth terminal W4 on the secondary winding side is connected to the anode electrode of the secondary winding.

The pump transformer TRS2 has the first terminal W1 and the second terminal W2 on the first winding side and the third terminal W3 and the fourth terminal W4 on the second winding side . The third terminal W3 on the second secondary winding side is located at a position facing the first terminal W1 on the first primary winding side of the pump transformer TRS2 and the second terminal W2 on the secondary side of the first transformer TRS2, And the fourth terminal W4 on the side of the secondary winding.

The anode of the pump diode DP is connected to the fourth terminal W4 of the pump transformer TRS2 on the second winding side and the anode electrode of the pump diode TRS2 is connected to one end of the tank capacitor CP and the second electrode of the second pump switch BT2 The cathode electrode is connected.

The tank capacitor CP is connected at one end to the cathode electrode of the pump diode DP and to the second electrode of the second pump switch BT2 and is connected to the low potential voltage output line GND and the secondary winding of the pump transformer TRS2 And the other end is connected to the third terminal W3.

The first pump switch BT1 has a gate electrode connected to the first output terminal of the pump control unit MCU, a first electrode connected to the other end of the pump inductor LP and a low potential voltage output line GND and a pump transformer The second electrode is connected to the third terminal W3 on the second winding side of the second winding TRS2. The first pump switch BT1 is turned on or off by the first pump switch signal outputted through the first output terminal of the pump control unit MCU.

The second pump switch BT2 has a gate electrode connected to the second output terminal of the pump control unit MCU and a first electrode connected to the other end of the pump inductor LP and connected to the cathode electrode of the pump diode DP and the tank capacitor CP is connected to one end of the second electrode. The second pump switch BT2 is turned on or off by the second pump switch signal outputted through the second output terminal of the pump control unit MCU.

The bridge switch BSW has a first electrode connected to one end of the pump inductor LP and a second electrode connected to the high potential output line Vout of the second power conversion unit LLC and the pump control unit MCU A control electrode is connected. The bridge switch BSW is turned on or off in response to the bridge switch control signal BSWC output from the pump control unit MCU. The bridge switch BSW is included in the second power conversion unit LLC or the power control unit CNT instead of the third power conversion unit Pump, and its affiliation can be changed.

The bridge switch BSW is turned off for electrical separation between the second power source conversion unit LLC and the third power source conversion unit Pump in the voltage balanced state. The bridge switch BSW separates the second power conversion unit LLC and the third power conversion unit Pump after the voltage of the power supply unit changes. The bridge switch BSW maintains the turn-on during the voltage variation period, while maintaining the turn-off during the voltage balance period after the voltage variation ends.

During the voltage variable period, the pump control unit MCU turns on the bridge switch BSW, turns on / off the pump switches BT1 and BT2, and changes the reference voltage Vref, And performs a control operation for varying the voltage. The relationship between the turn-on time of the bridge switch BSW and the change time of the reference voltage Vref can be set to the "turn-on time of the bridge switch BSW ≧ change time of the reference voltage Vref".

During the voltage equilibration period, the pump control unit MCU turns off the bridge switch BSW, turns off the pump switches BT1 and BT2, maintains the reference voltage Vref, Output line between the first power conversion unit and the third power conversion unit (Pump) is interrupted, and the output of the second power conversion unit (LLC) may shake (mutual interference between the parasitic resonance and the two circuits).

However, if the bridge switch BSW is disposed between the input / output line between the second power conversion unit LLC and the third power conversion unit Pump and the bridge switch BSW is turned off, The parasitic resonance component generated between the output part and the input part of the third power conversion part (Pump) is eliminated (or improved) due to the electrical separation. In addition, it has been shown that the output efficiency of the power supply unit can be rapidly changed by the operation of the bridge switch BSW, while maintaining the same efficiency as in the first embodiment.

The pump inductor LP is connected at one end to the bridge switch BSW connected to the high potential output line Vout of the second power conversion unit LLC and connected to the first pump switch BT1 and the second pump switch BT2, And the other end is connected to the first electrode of the second electrode.

The pump control unit MCU outputs a signal for operating the third power conversion unit Pump in which the output voltage of the power supply unit (or the second power conversion unit) is variable (or momentarily) The reference voltage Vref is changed to change the voltage level of the reference voltage Vref. The pump control unit (MCU) can be interlocked with the timing control unit or the like. When a signal for changing the voltage of the power supply unit is supplied from the timing control unit, the pump control unit MCU changes the reference voltage Vref accordingly.

The main control unit HBC outputs main switch signals STC for turning on or off the main switches ST1 and ST2. The pump control unit (MCU) outputs pump switch signals (SWC) for controlling the pump switches (BT1, BT2) to be turned on or off. The main control unit (HBC) and the pump control unit (MCU) are connected via a voltage change line.

In the main control unit HBC, the voltage value of the internal reference voltage Vref is varied by the voltage change signal provided from the pump control unit MCU. The frequency of the main switch signals STC output from the main control unit HBC also changes if the voltage value of the reference voltage Vref is varied by the voltage change signal provided from the pump control unit MCU.

The power supply unit according to the second embodiment includes pump switches capable of transmitting bi-directional power between the output capacitor CO of the second power conversion unit LLC and the tank capacitor CP of the third power supply conversion unit Pump in parallel It is connected and can exchange current quickly.

In the power supply unit according to the second embodiment, the second power conversion unit (LLC) basically performs the ZVS. However, the pump switches of the third power converter unit perform ZVS only in the voltage balanced state. That is, the pump switches of the third power converter Pump are hard switched only in the operation in which the output voltage is variable.

The power supply unit according to the second embodiment can overcome the limit of the output voltage variable time and can perform the simple bidirectional current transportation control (bidirectional power transmission by the duty change). Since the power supply unit according to the second embodiment carries the current between the output capacitor CO of the second power source conversion unit LLC and the tank capacitor CP of the third power source conversion unit Pump, 3 power converter (pump).

As described above, the signal generator PWM of the main control unit HBC has a main switching unit SW1 for switching the main switches ST1 and ST2 corresponding to the feedback signal FB transmitted through the output terminal of the comparator COMP, The frequency of the switch signals STC is varied. That is, the voltage conversion capability of the second power conversion unit LLC is related to the frequency of the main switch signals STC, and the factors that determine the voltage conversion capability are the high potential Vout and the reference voltage Vref.

In the second embodiment of the present invention, the reference voltage Vref is changed by a better modulation method than the first embodiment.

18, the power supply unit according to the first embodiment senses the output voltage of the second power conversion unit LLC for quick voltage change and outputs the second power conversion unit LLC based on the sensed voltage. The frequency of the main switch signals STC is varied.

To this end, the main control unit HBC senses the high-potential voltage Vout, which is the output voltage of the second power conversion unit LLC. The feedback error amplifier of the main control unit HBC detects the main switch signals STC corresponding to the sensed high potential voltage Vout and the fixed or varying reference voltage Vref ).

When the power supply unit (or the power conversion units) according to the first embodiment varies (or controls) the reference voltage Vref to change the voltage quickly, the voltage of the negative voltage input terminal of the comparator included in the main control unit HBC The change must be variable like an ideal waveform. However, in the case of the power supply unit according to the first embodiment, the voltage at the negative voltage input terminal of the comparator may not change rapidly due to the influence of the resistance, the parasitic capacitance component, and the like.

For this reason, the power supply unit according to the first embodiment can quickly change the output voltage, but there may be a limit. In addition, the third power supply unit has a structure of a third power supply unit provided for a fast output voltage, but may be affected by a change in the reference voltage Vref and may be unstable in a voltage variable operation.

As shown in FIG. 19, the main control unit (HBC) according to the second embodiment includes a voltage sensing unit (FEA) and a signal generating unit (PWM). The voltage sensing unit FEA compares the current output voltage with a desired reference voltage Vref to calculate an error and controls the second power conversion unit LLC in a direction that minimizes the generated error. Therefore, the voltage sensing unit (FEA) may be referred to as a feedback error amplifier circuit (Feedback Error Amplifier).

The voltage sensing unit FEA outputs the feedback signal FB based on the high potential voltage Vout and the reference voltage Vref. The form of the feedback signal FB output from the voltage sensing unit FEA is varied corresponding to the reference voltage Vref. The signal generating unit PWM generates the main switch signals STC in response to the feedback signal FB output from the voltage sensing unit FEA.

The voltage sensing unit FEA includes a comparator COMP, E / A, resistors R1 to R3, Ra and Rb and capacitors C1, C2 and C3 in order to minimize errors. The first resistor R1 has one end connected to the other end of the first capacitor C1 and the other end connected to the positive voltage input terminal (+) of the comparator COMP. The second resistor R2 is connected at one end to the positive voltage input terminal (+) of the comparator COMP and at the other end to the node to which the first voltage dividing resistor Ra and the second voltage dividing resistor Rb are connected. The third resistor R3 is connected at one end to the negative voltage input terminal (-) of the comparator COMP and at the other terminal to the terminal to which the reference voltage Vref is input.

The first capacitor C1 has one end connected to the output terminal of the comparator COMP and the other end connected to one end of the first resistor R1. The second capacitor C2 has one end connected to one end of the first capacitor C1 and the other end connected to the other end of the first resistor R1 and the positive voltage input terminal (+) of the comparator COMP. The third capacitor C3 is connected at one end to the negative voltage input terminal (-) of the comparator COMP and at the other end to the low potential voltage output line GND.

One end of the first voltage-dividing resistor Ra is connected to the high-potential voltage output line Vout of the second power-source conversion unit LLC and the other end thereof is connected to one end of the second voltage-dividing resistor Rb. The second voltage-dividing resistor Rb has one end connected to the other end of the first voltage-dividing resistor Ra and the other end connected to the low-potential voltage output line GND.

8, 9 and 20 (a), the first embodiment differs from the first embodiment in that the reference voltage VreF is varied to an ideal waveform in order to vary the output voltage of the power supply unit, The waveform of the reference voltage Vref appearing at the input terminal of the comparator COMP becomes a distorted waveform including the RC delay.

Accordingly, even if the voltage is instantaneously changed quickly due to the operation of the third power converter Pump, the output voltage of the second power converter LLC can not be kept constant because the reference voltage Vref is applied again And moves along the reference voltage Vref. That is, the output voltage of the power supply unit can not change rapidly, and is influenced by the reference voltage (Vref), which causes unstable driving in the voltage variable operation.

As shown in FIGS. 17, 19, 20 (b), 21 and 22, the second embodiment overdrives the reference voltage Vref in order to minimize the RC delay effect of the voltage sensing unit FEA. (over driving).

For example, the reference voltage Vref is a voltage having a specific function form such as a negative influence (-EXP) function as shown in FIG. 21, or a variable voltage VM is generated as shown in FIG. 21, The variable voltage VM can be generated by a step voltage having a step-like shape. At this time, the RC delay effect also varies depending on the level (Vl) and the time (Vt) of the variable voltage (VM) whose reference voltage (Vref) varies. Therefore, the level Vl and the time Vt of the variable voltage VM may vary depending on the circuit constituting the power supply unit.

As a result of inputting an artificial variable voltage (VM) in the above form, the RC delay problem at the negative voltage input (-) of the comparator (COMP) is eliminated or relaxed and the waveform close to the ideal step function . Therefore, the power supply unit according to the second embodiment can generate the reference voltage Vref in a form that can be stabilized within the optimum variable speed and the optimum time after the variable, and can quickly and stably control the output voltage .

23 and 24 are waveform diagrams for comparing and explaining main control features of the power supply unit according to the first embodiment and the second embodiment. The difference between the first embodiment and the second embodiment will be clarified with reference to the shape of the circular shape shown in Figs. 23 and 24, in addition to the following description.

As shown in FIG. 23, main control features of the power supply unit according to the first embodiment are as follows.

1. LLC Ref. As can be seen from the voltage, the reference voltage (Vref) changes in step waveform when the voltage change is required.

2. Error Amp Input Ref. As seen from the voltage waveform, the reference voltage (Vref) is distorted by the RC Delay.

3. As can be seen from the Boost Switch Duty Ratio, the duty of the pump switches is controlled to control the operation of the third power converter.

4. As can be seen from the LLC output voltage, after the operation of the third power converter Pump, the output voltage of the power supply unit follows the reference voltage Vref and is not stabilized and distortion occurs.

5. As can be seen from the Pump transport current, when the current is transported from the second power conversion unit LLC to the tank capacitor, the current sinks downward convexly, and the current from the tank capacitor to the second power conversion unit LLC When it becomes up, it rises upward convexly.

As shown in Fig. 24, the main control features of the power supply unit according to the second embodiment are as follows.

1. As can be seen from the Bump Bridge signal, the bridge switch is turned on only during the operation of the third power conversion unit (Pump).

2. LLC Ref. As can be seen from the voltage, the reference voltage (Vref) changes with a specific function waveform when the voltage change is required.

3. Error Amp Input Ref. As seen from the voltage waveform, the distortion of the reference voltage (Vref) by the RC delay is minimized.

4. As can be seen from the Boost Switch Duty Ratio, the duty of the pump switches is controlled to control the operation of the third power converter.

5. As can be seen from the LLC output voltage, the output voltage of the power supply unit is stabilized even after the operation of the third power converter unit.

6. As can be seen from the Pump transport current, when the current is transported from the second power conversion unit LLC to the tank capacitor, it is lowered slightly downward (with a lower width than in the first embodiment) 2 power converter (LLC).

The power supply unit according to the second embodiment can maintain a quick voltage change and a stable output. In addition, the power supply unit according to the second embodiment can change the reference voltage in the form of a specific function for quick and stable voltage change, electrically isolate the pump circuit and the main circuit from each other only in the voltage balanced state, There is an effect that can be done. In addition, the power supply unit according to the second embodiment operates only when the pump switches change the output voltage, and there is no power consumed in the equilibrium state. In addition, since the hard switching period of the power supply unit according to the second embodiment is very short, efficiency loss due to switching can be reduced. In addition, the power supply unit according to the second embodiment can overcome the limit of the output voltage variable time and can perform simple bidirectional current transportation control (bidirectional power transfer by duty change). In addition, the power supply unit according to the second embodiment is capable of rapidly changing the voltage while preventing the efficiency loss of the output stage by varying the feedback signal and the switching duty ratio. Further, since the power supply unit according to the second embodiment has the above-described driving characteristics and performance, it can exhibit a greater effect when applied to a display device that needs to rapidly change the high-potential voltage.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

110: image supply unit 120: timing control unit
130: scan driver 140:
150: Display panel 180: Power supply unit
LLC: Second power conversion section TRS1: Main transformer
CO: Output capacitor Pump: Third power conversion section
TRS2: Pump Transformer BT1, BT2: Pump Switches
LP: Pump inductor DP: Pump diode
CP: Tank Capacitor BSW: Bridge Switch

Claims (18)

A first DC power conversion unit having a main transformer for converting a first DC voltage supplied from the outside and outputting the first DC voltage to a second DC voltage,
And a second DC power supply having a pump transformer for converting the second DC voltage into a third DC voltage,
And the second DC power conversion unit is connected to the first DC power conversion unit in the form of a parallel stage capable of bi-directional power transfer. The method according to claim 1,
The primary winding side of the pump transformer
And a power supply unit connected to the secondary winding side of the main transformer in a form of a parallel stage. 3. The method of claim 2,
Wherein the first DC power converting unit includes an output capacitor located in a high-potential voltage output line,
Wherein the second DC power conversion unit includes a tank capacitor located on a second secondary winding side of the pump transformer,
And the second DC power conversion unit includes pump switches for bi-directional power transfer between the output capacitor and the tank capacitor. The method of claim 3,
The pump switches
ZVS (Zero Voltage Switching) power supply only in voltage balanced state. The method of claim 3,
When the duty of at least one of the pump switches is increased, the output voltage through the high-potential voltage output line of the first DC power converting part decreases with the voltage charging of the tank capacitor,
Wherein when the duty of at least one of the pump switches is reduced, the output voltage through the high-potential voltage output line of the first DC power converting part increases with the voltage discharge of the tank capacitor. The method according to claim 1,
A main control unit for changing a switching frequency of the first DC power supply unit,
And a pump controller for controlling a variable speed of the second DC power converter and outputting a voltage change signal for varying the switching frequency of the first DC power converter. The method according to claim 6,
The second DC power source conversion unit
The first terminal on the first primary winding side is connected to the fifth terminal on the second secondary winding side of the main transformer and the second terminal on the first primary winding side is connected to the low potential voltage output line of the first DC power conversion section A pump transformer,
A pump diode having an anode electrode connected to the fourth terminal on the second winding side of the pump transformer and a cathode electrode connected to the tank capacitor,
A tank capacitor whose one end is connected to the cathode electrode of the pump diode and whose other end is connected to a low potential voltage output line of the first DC power converting unit and a third terminal on the second secondary winding side of the pump transformer,
A pump inductor whose one end is connected to the high potential voltage output line of the first DC power source conversion unit,
A gate electrode is connected to a first output terminal of the pump control unit, a first electrode is connected to the other end of the pump inductor, and a low potential voltage output line of the first DC power converting unit and a third A first pump switch to which a second electrode is connected,
And a second pump switch having a gate electrode connected to a second output terminal of the pump control unit, a first electrode connected to the other end of the pump inductor, and a cathode electrode of the pump diode and a second electrode connected to one end of the tank capacitor Power supply. The method according to claim 1,
Further comprising a bridge switch located between an output of the first DC power converter and an input of the second DC power converter,
Wherein the bridge switch is turned off for electrical separation between the first direct current power converting part and the second direct current power converting part in a voltage balanced state. 8. The method of claim 7,
Further comprising a bridge switch having a first electrode connected to one end of the pump inductor, a second electrode connected to a high potential output line of the first DC power converting unit, and a control electrode connected to the pump control unit,
Wherein the bridge switch is turned on or off in response to a bridge switch control signal output from the pump control unit. 8. The method of claim 7,
The pump control unit
A reference voltage for changing the switching frequency of the first DC power supply unit is supplied to the main control unit,
A power supply unit for changing the reference voltage to a step voltage having a negative exponential function form or a negative exponential function form when the output voltage of the first DC power source conversion unit is variable, A display panel for displaying an image,
And a power supply unit for outputting power necessary for the apparatus for driving the display panel,
The power supply unit
A first DC power conversion unit having a main transformer for converting a first DC voltage supplied from the outside and outputting the first DC voltage to a second DC voltage,
And a second DC power supply having a pump transformer for converting the second DC voltage into a third DC voltage,
And the first winding side of the pump transformer is connected to the secondary winding side of the main transformer in a parallel stage form. 12. The method of claim 11,
Wherein the first DC power converting unit includes an output capacitor located in a high-potential voltage output line,
Wherein the second DC power conversion unit includes a tank capacitor located on a second secondary winding side of the pump transformer,
Wherein the second direct-current power conversion unit includes pump switches for transmitting bi-directional power between the output capacitor and the tank capacitor. 13. The method of claim 12,
When the duty of at least one of the pump switches is increased, the output voltage through the high-potential voltage output line of the first DC power converting part decreases with the voltage charging of the tank capacitor,
And the output voltage through the high-potential voltage output line of the first DC power converting unit increases with the voltage discharge of the tank capacitor when the duty of at least one of the pump switches decreases. 14. The method of claim 13,
A main control unit for changing a switching frequency of the first DC power supply unit,
And a pump controller for controlling a voltage variable speed of the second DC power converter and outputting a voltage changing signal for varying the switching frequency of the first DC power converter. 15. The method of claim 14,
The second DC power source conversion unit
The first terminal on the first primary winding side is connected to the fifth terminal on the second secondary winding side of the main transformer and the second terminal on the first primary winding side is connected to the low potential voltage output line of the first DC power conversion section A pump transformer,
A pump diode having an anode electrode connected to the fourth terminal on the second winding side of the pump transformer and a cathode electrode connected to the tank capacitor,
A tank capacitor whose one end is connected to the cathode electrode of the pump diode and whose other end is connected to a low potential voltage output line of the first DC power converting unit and a third terminal on the second secondary winding side of the pump transformer,
A pump inductor whose one end is connected to the high potential voltage output line of the first DC power source conversion unit,
A gate electrode is connected to a first output terminal of the pump control unit, a first electrode is connected to the other end of the pump inductor, and a low potential voltage output line of the first DC power converting unit and a third A first pump switch to which a second electrode is connected,
And a second pump switch having a gate electrode connected to a second output terminal of the pump control unit, a first electrode connected to the other end of the pump inductor, and a cathode electrode of the pump diode and a second electrode connected to one end of the tank capacitor Display device. 12. The method of claim 11,
Further comprising a bridge switch located between an output of the first DC power converter and an input of the second DC power converter,
Wherein the bridge switch is turned off for electrical separation between the first direct current power converting unit and the second direct current power converting unit in a voltage balanced state. 16. The method of claim 15,
Further comprising a bridge switch having a first electrode connected to one end of the pump inductor, a second electrode connected to a high potential output line of the first DC power converting unit, and a control electrode connected to the pump control unit,
Wherein the bridge switch is turned on or off in response to a bridge switch control signal output from the pump control unit. 16. The method of claim 15,
The pump control unit
A reference voltage for changing the switching frequency of the first DC power supply unit is supplied to the main control unit,
And changes the reference voltage to a step voltage having a negative exponential function form or a negative exponential function form if the output voltage of the first DC power source conversion unit is variable, the step voltage having a stepped form.

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