CN111724747B

CN111724747B - Display device and power supply starting method

Info

Publication number: CN111724747B
Application number: CN201910212377.6A
Authority: CN
Inventors: 韩文涛; 高宽志
Original assignee: Hisense Visual Technology Co Ltd
Current assignee: Hisense Visual Technology Co Ltd
Priority date: 2019-03-20
Filing date: 2019-03-20
Publication date: 2021-10-22
Anticipated expiration: 2039-03-20
Also published as: CN111724747A

Abstract

The application provides a display device and a power supply starting method, wherein the display device comprises a power supply board: be equipped with the LLC unit on the power strip, the LLC unit includes: the device comprises an LLC control unit, an LLC power conversion unit, a voltage feedback signal unit and a current feedback signal unit; the voltage feedback signal unit is used for feeding back a first output voltage related signal to the LLC control unit; the current feedback signal unit is used for feeding back an output current signal to the LLC control unit; and the LLC control unit is used for controlling the frequency of the LLC power conversion unit according to the output current signal and controlling the duty ratio of a driving signal of the first voltage regulating switch according to the first output voltage related signal so as to stabilize the output current and the first output voltage. Constant voltage and constant current are realized through the single-stage LLC control unit, and compared with the prior art, the DC/DC conversion unit is saved, so that the cost is saved, and the efficiency is improved.

Description

Display device and power supply starting method

Technical Field

The present disclosure relates to power supply technologies, and particularly to a display device and a power supply starting method.

Background

As the demand for obtaining information is continuously increasing, various types of display devices, such as computers, televisions, projectors, and the like, are being developed. The power supply circuit is one of the most important circuit structures in the display device, and the power supply circuit can provide electric energy for the display device, so that the display device can normally operate. Some display devices are provided with independent power panels, and some display devices combine the power panels and the main board into a whole.

Taking a display device provided with an independent power board as an example, a structure of the display device is described, referring to fig. 1a, fig. 1a is a schematic structural diagram of the display device provided with the independent power board, as shown in fig. 1a, the display device includes a panel 1, a backlight assembly 2, a main board 3, a power board 4, a rear case 5 and a base 6. Wherein, the panel 1 is used for presenting pictures for users; the backlight assembly 2 is located below the panel 1, usually some optical assemblies, for supplying sufficient brightness and light sources with uniform distribution, so that the panel 1 can normally display images, the backlight assembly 2 further includes a back plate 21, the main plate 3 and the power supply board 4 are arranged on the back plate 21, usually some convex hull structures are formed by punching on the back plate 21, and the main plate 3 and the power supply board 4 are fixed on the convex hulls through screws or hooks; the rear shell 5 is covered on the panel 1 to hide the parts of the display device such as the backlight assembly 2, the main board 3 and the power panel 4, and the like, thereby achieving the effect of beautiful appearance; and a base 6 for supporting the display device.

The power panel of the display device needs to supply more than two types of electric signals to the load, for example, a main board needs a constant voltage dc power, an accompanying sound needs a higher constant voltage, and an LED module (i.e., a backlight module) needs a constant current dc power. Therefore, the power panel obtains different electric signals by arranging the transformer, but the output of the same transformer has the problem of cross adjustment, and the requirement that the multi-path output of the same transformer can meet the constant voltage and constant current cannot be ensured.

In the prior art, different types of loads are generally powered by adding a DC/DC conversion unit, which results in higher cost and low efficiency.

Disclosure of Invention

The application provides a display device and a power supply starting method, which aim to overcome the defects of high cost, low efficiency and the like of a power supply in the prior art.

The present application provides a display device in a first aspect, including the power strip, be equipped with the LLC unit on the power strip, the LLC unit includes: the device comprises an LLC control unit, an LLC power conversion unit, a voltage feedback signal unit, a current feedback signal unit and a first voltage regulation switch;

the voltage feedback signal unit is respectively connected with an output end of the first output voltage and the LLC control unit; the voltage feedback signal unit is used for feeding back a first output voltage related signal to the LLC control unit;

the current feedback signal unit is respectively connected with the output end of the second output voltage and the LLC control unit; the current feedback signal unit is used for feeding back an output current signal to the LLC control unit;

the LLC control unit is used for controlling the frequency of the LLC power conversion unit according to the output current signal and controlling the duty ratio of a driving signal of a first voltage regulation switch according to the first output voltage related signal so as to stabilize the output current and the first output voltage;

the first voltage regulation switch is respectively connected with the LLC control unit and the LLC power conversion unit.

Optionally, the LLC power conversion unit includes: LLC power switches and transformers;

the LLC power switch is respectively connected with the PFC unit and the transformer; the transformer is also connected with the first voltage adjusting switch;

the LLC power switch and the transformer form a resonant conversion circuit, and the LLC power switch and the transformer output the second output voltage and the first output voltage after being adjusted by the first voltage adjusting switch under the control of the LLC control unit.

Optionally, the first voltage adjusting switch is connected in series with an output winding of the first output voltage of the LLC power conversion unit, for adjusting the first output voltage.

Optionally, the LLC control unit includes an error operational amplifier and a voltage-controlled oscillator;

the error operational amplifier is respectively connected with the voltage feedback signal unit and the voltage-controlled oscillator; the voltage controlled oscillator is also connected with the LLC power conversion unit;

the error operational amplifier is used for comparing the first output voltage related signal with a preset constant voltage signal and performing proportional integral operation to obtain an error voltage;

the error operational amplifier is also used for comparing the output current signal with a preset constant current signal and carrying out proportional integral operation to obtain an error current;

and the voltage-controlled oscillator is used for outputting the frequency of the LLC power conversion unit according to the error voltage or the error current.

Optionally, the first output voltage is a motherboard voltage, and the output current is a current required by the backlight assembly;

when the backlight is turned off, the LLC control unit is further configured to control the frequency of the LLC power conversion unit according to the first output voltage-related signal, so as to stabilize the first output voltage.

Optionally, the LLC unit further includes: a second voltage regulating switch;

the LLC power conversion unit is also used for generating a third output voltage under the control of the LLC control unit;

the second voltage adjusting switch is connected in series with an output winding of the third output voltage of the LLC power conversion unit, and is configured to adjust the third output voltage.

Optionally, the voltage feedback signal unit includes: two voltage dividing resistors; the input of the voltage feedback signal unit is the first output voltage, and the output is the first output voltage related signal after voltage division.

Optionally, the current feedback signal unit includes: a current collection resistor connected in series with the backlight assembly;

the input of the current feedback signal unit is voltage VLED, and the output is the collected output current signal.

Optionally, a PFC unit is further disposed on the power board, and the PFC unit includes a PFC inductor, an auxiliary isolation winding, and a PFC control unit; the auxiliary isolation winding is arranged on one side of the PFC inductor; and the auxiliary isolation winding is used for inducing voltage with the PFC inductor to supply power to the LLC control unit.

A second aspect of the present application provides a power supply starting method for the display device provided in the first aspect, the method including:

acquiring a first voltage, wherein the first voltage is the voltage at an alternating-current high-voltage discharge resistor;

inputting the first voltage to a PFC control unit to start the PFC control unit;

acquiring a second voltage, wherein the second voltage is induced by an auxiliary isolation winding of the PFC unit and a PFC inductor;

inputting the second voltage to the LLC control unit to start the LLC control unit.

According to the display device and the power supply starting method, the voltage feedback signal unit feeds back the first output voltage related signal, and the current feedback signal unit feeds back the output current signal, so that the LLC control unit can control the frequency of the LLC power switch according to the output current signal to realize the constant current of the output current, and the duty ratio of the first voltage regulation switch is controlled according to the first output voltage related signal, thereby realizing the constant voltage of the first output voltage, namely, the constant voltage and the constant current are realized through the single-stage LLC control unit. And through three loop control of the voltage control loop, the current control loop and the duty ratio control loop, the constant-voltage direct current can be output to supply power to the mainboard when the backlight is closed, and the constant-voltage direct current can be output to supply power to the mainboard when the backlight is opened under the condition of ensuring the constant-current direct current power supply of the backlight assembly.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1a is a schematic structural diagram of a display device with an independent power panel;

FIG. 1b is a schematic diagram of a power architecture of a television;

fig. 2 is a schematic structural diagram of an LLC unit according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of a voltage feedback signal unit according to an embodiment of the present disclosure;

fig. 4 is a schematic structural diagram of a current feedback signal unit according to an embodiment of the present disclosure;

fig. 5 is a schematic structural diagram of an LLC control unit according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of an LLC power conversion unit according to an embodiment of the present application;

FIG. 7 is a schematic diagram of a control loop provided in an embodiment of the present application;

FIG. 8 is a schematic diagram of a control loop when the backlight is turned off according to an embodiment of the present disclosure;

fig. 9 is a schematic diagram of a control loop when a backlight is turned on according to an embodiment of the present application;

fig. 10 is an exemplary schematic diagram of an LLC unit according to an embodiment of the present application;

fig. 11 is a schematic diagram illustrating a driving signal control principle of the S1 switch according to an embodiment of the present application;

fig. 12 is a schematic structural diagram of an LLC unit according to another embodiment of the present application;

fig. 13 is an exemplary circuit diagram of a television power architecture according to an embodiment of the present application;

FIG. 14 is a schematic diagram of a power supply according to an embodiment of the present application;

fig. 15 is a schematic diagram of a power supply according to an embodiment of the present application.

With the above figures, there are shown specific embodiments of the present application, which will be described in more detail below. These drawings and written description are not intended to limit the scope of the disclosed concepts in any way, but rather to illustrate the concepts of the disclosure to those skilled in the art by reference to specific embodiments.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms referred to in this application are explained first:

LLC: a resonant circuit.

PFC: power Factor Correction, Power Factor Correction. The power factor refers to a relationship between the effective power and the total power consumption (apparent power), that is, a ratio of the effective power divided by the total power consumption (apparent power). Basically, the power factor can measure the effective utilization degree of the power, and when the power factor value is larger, the power utilization rate is higher. The power factor is a parameter for measuring the power efficiency of the electric equipment, and the low power factor represents the low power efficiency. A technique for increasing the power factor of a powered device is known as power factor correction.

A voltage-controlled oscillator: the oscillator is characterized in that an oscillating circuit (VCO) with the output frequency corresponding to the input control voltage, an oscillator VCO with the frequency being a function of the input signal voltage, and the working state of the oscillator or the element parameters of the oscillating circuit are controlled by the input control voltage to form a voltage-controlled oscillator.

EMI: electro Magnetic Interference (EMI). EMI filtering refers to the elimination of electromagnetic interference by filtering.

The LLC unit provided by the embodiment of the application is suitable for a scene of supplying power to a load which needs constant voltage direct current and constant current direct current, such as a television and other equipment with a display device, a mainboard of the display device needs constant voltage direct current, a backlight assembly LED needs constant current direct current, and the like. Of course not limited to a television.

Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the following examples, "plurality" means two or more unless specifically limited otherwise.

The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments. Embodiments of the present invention will be described below with reference to the accompanying drawings.

Taking a television as an example to introduce its power architecture, referring to fig. 1b, fig. 1b is a schematic diagram of a television power architecture, as shown in fig. 1b, the television power architecture may include: a rectifying unit 101, a Power Factor Correction (PFC) unit 102, a resonant converter (LLC) unit 103, a Power supply circuit 104, a main board 105, a backlight assembly 106, and a display main body 107. Since the main board requires a constant voltage DC power supply and the backlight assembly requires a constant current DC power supply, a DC conversion DC/DC unit is also required in order to satisfy the requirements of constant voltage and constant current.

A synchronous rectification circuit (not shown in fig. 1 b) is included in the LLC unit 103. The PFC unit 102 is connected to the LLC unit 103, and the LLC unit 103 is connected to the power supply circuit 104.

The rectifying unit 101 is configured to rectify an input ac power and input a full-wave signal to the PFC unit 102. An Electromagnetic Interference (EMI) filter unit 109 may be connected to the ac power input to the PFC unit 102 to perform high-frequency filtering on the input ac power.

The PFC unit 102 generally includes a PFC inductor, a switching power device, and a PFC control chip, and mainly performs power factor correction on an input ac power source to output a stable dc bus voltage (e.g., 380V) to the LLC unit 103. The PFC unit 102 may effectively improve the power factor of the power supply, and ensure the same phase of the voltage and the current.

The LLC unit 103 may include an LLC control unit 1031 and an LLC power conversion unit 1032, the LLC power conversion unit 1032 may employ a dual MOS tube LLC resonant conversion circuit, and typically a synchronous rectification circuit is provided in the LLC unit 103, and the synchronous rectification circuit may mainly include a transformer, a controller, two MOS tubes, and a diode. In addition, the LLC power conversion unit 1032 may further include a Pulse Frequency Modulation (PFM) circuit, a capacitor, an inductor, and other components. The LLC unit 103 may specifically step down or step up the dc bus voltage input by the PFC unit 102, and output a constant voltage to a load, where the load includes a main board 105, a backlight assembly 106, and a display main body 107. The LLC control unit 1031 is connected to the power supply circuit 104 and can control whether the power supply circuit 104 is on or off. The power supply circuit 104 generally includes a switching element, such as a MOS transistor, and the LLC control unit 1031 controls the conduction state of the MOS transistor by controlling the voltage of the source and the gate of the MOS transistor.

According to the television power supply framework, in order to meet the requirements of constant voltage of the main board and constant current of the backlight assembly, the direct current conversion DC/DC unit is required to be added to meet the requirement of constant voltage direct current of the main board under the condition of ensuring the constant current direct current of the backlight assembly, so that the cost is high, and the efficiency is low.

In order to solve the above problem of the television power supply architecture, an embodiment of the present application provides an LLC unit for controlling output of a constant voltage direct current and a constant current direct current.

As shown in fig. 2, for a schematic structural diagram of the LLC unit provided in this embodiment, the LLC unit 103 includes: an LLC control unit 1031, an LLC power conversion unit 1032, a voltage feedback signal unit 1033, a current feedback signal unit 1034, and a first voltage adjustment switch 1035.

Wherein the voltage feedback signal unit 1033 is connected to the output terminal a1 of the first output voltage and the LLC control unit 1031, respectively, and the voltage feedback signal unit 1033 is configured to feed back the first output voltage related signal to the LLC control unit 1031;

the current feedback signal unit 1034 is respectively connected to the output terminal a2 of the voltage VLED (i.e. the second output voltage) and the LLC control unit 1031, and is configured to feed back an output current signal to the LLC control unit 1031;

the LLC control unit 1031 is configured to control the frequency of the LLC power conversion unit 1032 according to the output current signal, and control the duty ratio of the driving signal of the first voltage adjustment switch 1035 according to the first output voltage-related signal, so as to stabilize the output current and the first output voltage.

The first voltage adjustment switch 1035 is connected to the LLC control unit 1031 and the LLC power conversion unit 1032, respectively, and specifically, the first voltage adjustment switch 1035 is connected in series with an output winding of the first output voltage of the LLC power conversion unit 1032 for adjusting the first output voltage.

The LLC power conversion unit 1032 is configured to convert the direct current output by the PFC unit 102 according to the frequency output by the LLC control unit 1031 to obtain a voltage VLED required by the output current, and obtain the first output voltage V1 after being adjusted by the first voltage adjustment switch 1035.

Optionally, the first output voltage related signal may be the first output voltage or a voltage of a certain proportion of the first output voltage, for example, as shown in fig. 3, a schematic structural diagram of the voltage feedback signal unit provided in this embodiment may divide the voltage by two resistors to obtain a part of the voltage of the first output voltage. That is, the voltage feedback signal unit 1033 may include two voltage dividing resistors, which are input to the first output voltage V1 output by the LLC power conversion unit 1032 and output a divided first output voltage related signal. Wherein, R1 and R2 are resistors, and the specific resistance values of R1 and R2 can be set according to actual requirements.

Alternatively, the output current signal may collect the output current by connecting a current collecting resistor in series with a constant current driven backlight assembly (such as an LED). That is, the current feedback signal unit 1034 may include a backlight assembly and a current collecting resistor connected in series, and input the constant current voltage VLED and output the collected output current. Exemplarily, as shown in fig. 4, a schematic structural diagram of a current feedback signal unit provided for the present embodiment is shown.

Alternatively, the LLC control unit 1031 may include an error operational amplifier and a voltage-controlled oscillator; as shown in fig. 5, a schematic structural diagram of the LLC control unit provided in this embodiment is shown. The error operational amplifier is connected to the voltage feedback signal unit 1033, and the error operational amplifier may be configured to compare the first output voltage related signal with a preset constant voltage signal and perform a proportional-integral operation to obtain an error voltage; the error operational amplifier may be further configured to compare the output current signal with a preset constant current signal and perform a proportional integral operation to obtain an error current, and a preset constant voltage signal used for comparing with the fed back first output voltage related signal and a preset constant current signal used for comparing with the fed back output current signal may be preset in the LLC control unit 1031. The error operational amplifier is further connected with a voltage-controlled oscillator, the voltage-controlled oscillator is connected with the LLC power conversion unit 1032, and the voltage-controlled oscillator is configured to adjust an oscillation frequency according to an error voltage or an error current obtained by the error operational amplifier, so as to control a frequency of an LLC power switch of the LLC power conversion unit 1032.

The LLC power conversion unit 1032 may include an LLC power switch and a transformer, forming a resonant conversion circuit, and as shown in fig. 6, for example, a schematic structural diagram of the LLC power conversion unit provided in this embodiment is shown. The LLC power switches V2 and V3 may be MOS transistors.

Optionally, when the output current is not needed, for example, when the backlight is turned off, the LLC control unit 1031 may further control the frequency of the LLC power switch according to the first output voltage related signal to realize the first output voltage constant voltage.

Optionally, the LLC unit 103 may be further connected to a power supply circuit 104 (not shown in fig. 2), and the power supply circuit 104 may be connected to the LLC control unit 1031 and the load, respectively, and the LLC control unit 1031 controls on/off of the power supply circuit 104, so as to control whether the LLC power conversion unit 1032 can supply power to the load. The LLC power conversion unit 1032 is capable of powering a load when the power supply circuit 104 is on, and the LLC power conversion unit 1032 is incapable of powering a load when the power supply circuit 104 is off. In practical applications, the power supply circuit 104 may include a switch element, such as a switch for controlling the on/off of the backlight assembly. The power supply circuit 104 may be implemented by MOS transistors, and the LLC control unit 1031 controls the conduction states of the MOS transistors by controlling the voltages of the sources and the gates of the MOS transistors.

In some embodiments, the LLC unit 103 is implemented in practice by using time-division control of the voltage feedback VFB and the current feedback IFB to supply power to the load in both the backlight on and off conditions. Illustratively, a television power supply is taken as an example for explanation, and as shown in fig. 7, a schematic diagram of a control loop provided in this embodiment is provided. The method adopts a mode of voltage feedback VFB and current feedback IFB time-sharing control, when the backlight is opened, the main loop adopts current feedback control, and the voltage of the main board adopts additional independent small voltage loop control; when the backlight is closed, the main circuit adopts the voltage feedback control of the main board to close the independent small voltage ring. As shown in fig. 8, a schematic diagram of a control loop when the backlight is turned off is provided in this embodiment. As shown in fig. 9, a schematic diagram of a control loop when the backlight is turned on is provided in this embodiment.

Specifically, the control loop includes a current control loop ICOMP, a voltage control loop VCOMP, and a duty cycle control loop DCOMP. The voltage control loop VCOMP is used for controlling the LLC power conversion unit to output constant-voltage direct current to supply power to the mainboard according to a signal fed back by the voltage feedback signal unit. The current control loop ICOMP is used for controlling the LLC power conversion unit 1032 to output a constant current direct current VLED to supply power to the backlight assembly according to a signal fed back by the current feedback signal unit. When the backlight is turned on, the backlight assembly and the main board need to be supplied with power at the same time, and at the moment, constant current and constant voltage need to be simultaneously realized, when the LLC power conversion unit 1032 ensures that constant-current direct current VLED is output to supply power to the backlight assembly, the voltage output by the LLC power conversion unit 1032 to the main board is easy to be unstable, at this moment, the duty ratio control loop DCOMP can be used for outputting PWM waveform with adjustable duty ratio under the condition of ensuring the constant current of the backlight assembly and is used for driving an N-MOS S1 switch, when the output voltage of a main board winding of the transformer is high, the duty ratio is reduced, when the output voltage of the main board winding of the transformer is low, the duty ratio is increased, and stable main board supply voltage is ensured to be output.

As an implementable manner, for example, as shown in fig. 10, an exemplary schematic diagram of an LLC unit is provided for this embodiment. Wherein, D1 and D2 play a role in rectification, C1 and C2 play a role in filtering, and S1 is the first voltage regulation switch. Wherein the LLC frequency control is part of the functionality of the LLC control unit. +12V is the first output voltage, i.e. the constant voltage dc required by the main board, VLED is the constant current dc required by the backlight LED.

The specific working principle of the control loop is as follows:

1. when the backlight is turned on

The frequency of the LLC power switch is controlled by a backlight current feedback loop ICOMP (current feedback, i.e. the current feedback signal unit 1034 feeds back an output current signal to the LLC control unit 1031), and the current control loop ICOMP controls the constant current output of the backlight assembly LED. At the moment, the transformer is controlled to output constant current for driving the backlight assembly, the voltage of a power supply winding of a main board of the transformer is not controlled and unstable, and in order to ensure that stable main board voltage can be output, an N-MOS switch S1 is connected in series to serve as a main board voltage adjusting switch (namely, a first voltage adjusting switch). The main board voltage feedback VFB (namely a first output voltage related signal fed back by the voltage feedback signal unit 1033) is connected to the DCOMP to form a voltage control small loop (namely a duty ratio control loop), the voltage control small loop and the current control loop are relatively independent, the voltage control small loop outputs a PWM waveform with adjustable duty ratio and is used for driving an N-MOS S1 switch.

2. When the backlight is off

The frequency of the LLC power switch is controlled (voltage feedback) by a main board voltage feedback loop VCOMP, the voltage control loop VCOMP controls the oscillation frequency of a voltage-controlled oscillator in an LLC control unit, and therefore the frequency of the LLC power switch is controlled through output, which is a main loop, and the LLC power conversion unit 1032 outputs constant-voltage direct current to supply power to the main board. At the moment, the voltage control small loop is closed, the N-MOS S1 is in a through state, and the LLC power conversion unit outputs constant-voltage direct current to supply power to the mainboard. At this time, the current feedback does not work, and the backlight is not controlled and unstable. Since the backlight is off, it is not affected.

3. When the backlight is on but in PWM dimming

As described above, a PWM high level corresponds to backlight on and a PWM low level corresponds to backlight off.

4. Working mode of voltage control small ring S1 switch

As shown in fig. 11, a schematic diagram of a driving signal control principle of the S1 switch provided in this embodiment is shown. Wherein Isec refers to a resonant tank circuit current of the LLC power conversion unit 1032, that is, a primary current of the transformer; LLC DRV refers to the drive of the LLC power switch; duty _ N refers to the Duty ratio of the driving signal of S1. In order to reduce the switching loss of the MOS, the MOS adopts a zero-current turn-off mode, namely, the MOS works in a ZCS mode. The turn-off time of the driving signal of S1 follows the turn-off of the MOS switch of the primary side LLC power conversion unit 1032, when the primary side MOS switch is turned off, the current of the transformer output winding crosses zero, at this time S1 is turned off, ensuring that it operates at zero current turn-off, and the turn-on time is controlled by the duty cycle control loop DCOMP.

In some embodiments, optionally, the LLC unit 103 can further include a second voltage regulation switch 1036. As shown in fig. 12, a schematic structural diagram of the LLC unit provided in this embodiment is shown.

The LLC power conversion unit 1032 is further configured to generate a third output voltage in combination with the second voltage regulation switch 1036, where the third output voltage may be a constant-voltage direct current required by accompanying sound and the like;

the second voltage regulating switch 1036 is connected in series with an output winding of the third output voltage of the LLC power conversion unit 1032 for regulating the third output voltage.

The second voltage regulating switch 1036 is logically related to the LLC power switch such that the second voltage regulating switch 1036, similar to the first voltage regulating switch 1035, also operates in the ZCS state. The specific working principle is similar to that of the first voltage regulating switch, and is not described herein again.

For example, in a display device of a television, a main board voltage requires +12V constant voltage direct current (i.e., a first output voltage), a sound voltage requires +16V constant voltage direct current (i.e., a third output voltage), a backlight assembly LED string requires constant current direct current VLED, and the like.

Alternatively, the second voltage regulating switch 1036 may be a MOS switch, such as an N-MOS switch, or any other switch that may be implemented.

In some embodiments, as shown in fig. 13, an exemplary circuit diagram of a television power architecture provided for the present embodiment is shown. The television power architecture shown in this figure is an exemplary application circuit. As shown IN fig. 13, AC _ IN refers to AC input, inductor L1, MOS transistor V1 and diode D1 constitute a PFC power unit, PFC IC refers to a PFC control unit, and PFC power unit and PFC control unit constitute PFC unit 102; MOS tubes V2 and V3 are LLC power switches, T1 is a transformer, a capacitor C1 and the transformer T1 form a resonant circuit, and V2, V3, C1 and T1 form an LLC power conversion unit 1032. LLC IC refers to LLC control unit 1031. The diodes D2 and D3 have a rectifying function, the MOS transistor V4 is a second voltage adjusting switch 1036 for adjusting the +16V second output voltage, and the capacitor C2 performs filtering. The diodes D4 and D5 rectify the +12V first output voltage via the MOS transistor V5 (i.e., the first voltage-regulating switch 1035), and the capacitor C3 performs filtering. The resistors R1 and R2 form a voltage feedback signal unit 1033, which inputs +12V voltage and outputs the voltage shared by R2 to be fed back to the LLC control unit 1031. D6, D7, D8 and D9 form a bridge rectifier circuit for rectifying and then outputting voltage VLED required by the LED lamp string, C5 and C6 for filtering, an MOS tube V6 is used for controlling the on-off of the LED lamp string, namely controlling the on-off of backlight, and D _ LED is the drive of the MOS tube V6.

The specific working principle is as follows: the alternating current is converted into high-voltage direct current after rectification and filtering, the high-voltage direct current is converted into constant-voltage direct current +12V by the LLC power conversion unit 1032 to supply power for the main board, the constant-voltage direct current +16V supplies power for the accompanying sound, and the constant-current direct current VLED supplies power for the backlight assembly. LLC control unit 1031 (which may be a chip) is a secondary control chip that receives backlight current feedback IFB and motherboard voltage +12V feedback VFB.

When the backlight is turned off: the frequency of the LLC power switch is feedback controlled by +12V voltage VFB, and constant voltage direct current (namely first output voltage) is output to supply power to the mainboard.

When the backlight is started: the frequency of the LLC power switch is controlled by the backlight current feedback IFB, and the Duty cycle control loop is active at the same time, VFB is fed back as the first output voltage related signal, and the LLC control unit 1031 controls the switching time of V5 according to the first output voltage related signal, the output signal Duty _ N, adjusts the voltage of this path to be stable, and outputs a stable +12V voltage to power the motherboard. Similarly, the switching time of the V4 is controlled, and the stable +16V voltage is output to supply power for the accompanying sound.

It should be noted that the present embodiment is only an exemplary embodiment, and is not a limitation of the present application. The specific implementation of the functions of each part may also be replaced by other manners, such as a rectifying part, and may be replaced by any implementable manner, which is not limited to the circuit structure in the figure.

The LLC unit provided by this embodiment, feedback the first output voltage related signal through the voltage feedback signal unit, the current feedback signal unit feeds back the output current signal, make the LLC control unit can control the frequency of the LLC power switch according to the output current signal, realize the constant current of the output current, and control the duty cycle of the first voltage regulating switch according to the first output voltage related signal, thereby realize the constant voltage of the first output voltage, namely realized constant voltage and constant current through the single-stage LLC control unit, compare with the prior art, DC/DC of the direct current conversion unit has been saved, thereby save the cost, and improve the efficiency. And through three loop control of the voltage control loop, the current control loop and the duty ratio control loop, the constant-voltage direct current can be output to supply power to the mainboard when the backlight is closed, and the constant-voltage direct current can be output to supply power to the mainboard when the backlight is opened under the condition of ensuring the constant-current direct current power supply of the backlight assembly.

The second embodiment of the present application provides a power supply, which is used for supplying power to a load of a display device. As shown in fig. 14, which is a schematic structural diagram of the power supply provided in this embodiment, the power supply 30 includes the LLC unit 103 provided in the foregoing embodiment.

Regarding the LLC unit in the present embodiment, detailed description has been made in the embodiment related to the LLC unit, and detailed description will not be made here.

According to the power supply provided by the embodiment, the voltage feedback signal unit feeds back the first output voltage related signal, and the current feedback signal unit feeds back the output current signal, so that the LLC control unit can control the frequency of the LLC power switch according to the output current signal, thereby realizing the constant current of the output current, and control the duty ratio of the first voltage regulation switch according to the first output voltage related signal, thereby realizing the constant voltage of the first output voltage, that is, the constant voltage and the constant current are realized by the single-stage LLC control unit. And through three loop control of the voltage control loop, the current control loop and the duty ratio control loop, the constant-voltage direct current can be output to supply power to the mainboard when the backlight is closed, and the constant-voltage direct current can be output to supply power to the mainboard when the backlight is opened under the condition of ensuring the constant-current direct current power supply of the backlight assembly.

The third embodiment of the present application provides a display device, which includes the power supply provided by the above embodiment. Specifically, the display device may include a power panel, and the LLC unit provided in the foregoing embodiments is provided on the power panel.

Optionally, a PFC unit may be further disposed on the power board of the display device, where the PFC unit includes a PFC inductor and an auxiliary isolation winding; the auxiliary isolation winding is arranged on one side of the PFC inductor; and the auxiliary isolation winding is used for inducing voltage with the PFC inductor to supply power to the LLC control unit.

According to the display device provided by the embodiment, the voltage feedback signal unit feeds back the first output voltage related signal, and the current feedback signal unit feeds back the output current signal, so that the LLC control unit can control the frequency of the LLC power switch according to the output current signal, thereby realizing the constant current of the output current, and control the duty ratio of the first voltage regulation switch according to the first output voltage related signal, thereby realizing the constant voltage of the first output voltage, that is, the constant voltage and the constant current are realized by the single-stage LLC control unit. And through three loop control of the voltage control loop, the current control loop and the duty ratio control loop, the constant-voltage direct current can be output to supply power to the mainboard when the backlight is closed, and the constant-voltage direct current can be output to supply power to the mainboard when the backlight is opened under the condition of ensuring the constant-current direct current power supply of the backlight assembly.

An embodiment of the present application provides a method for starting a power supply, which is used for starting a power supply including a PFC unit and an LLC unit provided in any one of the above embodiments.

The method comprises the following steps:

step 401, obtaining a first voltage, where the first voltage is a voltage at an ac high-voltage discharge resistor.

Step 402, inputting the first voltage to a PFC control unit to start the PFC control unit.

Step 403, obtaining a second voltage, where the second voltage is induced by the auxiliary isolation winding of the PFC unit and the PFC inductor.

Step 404, inputting the second voltage to the LLC control unit to start the LLC control unit.

Specifically, as shown in fig. 15, it is a schematic diagram of the power supply provided in this embodiment.

An auxiliary isolation winding L2 is added to a PFC inductor L1 in the PFC unit, so that the auxiliary isolation winding and the PFC inductor in the PFC unit induce voltage to supply power to a secondary LLC control unit. The first voltage is the voltage between the alternating current AC high voltage discharge resistors R1 and R2 in FIG. 15; the second voltage is the voltage induced by the auxiliary isolation winding L2. Alternatively, the first voltage and the second voltage may be rectified and filtered before being input to the PFC control unit and the LLC control unit. As shown in fig. 15, D2 and C1 are used to rectify and filter the first voltage, and D3 and C3 are used to rectify and filter the second voltage.

The main circuits in the dashed line frame portion are the same as those in fig. 13, wherein the inductors L1, D1, V1, V2, V3, and T1 of the PFC power unit are introduced in the above embodiments, and are not described again here. Here, R1, R2, D2 and C1 are different from the above-described embodiments. The function of C2 here is identical to C1 in fig. 13. Here, D4 is the rectification of the output voltage of +12V, D5 is the rectification of the output voltage of +16V, and D6 is the rectification of the output voltage of VLED. The first voltage regulating switch and the second voltage regulating switch here are not shown.

The PFC chip (PFC IC, namely a PFC control unit) takes electricity from an alternating current AC high-voltage discharge resistor (namely R1 and R2), starts the PFC chip, is rectified by a diode D2, and is filtered by a capacitor C1. An auxiliary isolation winding (a winding L2 outside a dotted line on the inductor of the PFC power unit in fig. 13) is added to the PFC inductor L1, voltage is induced by the PFC inductor and the auxiliary isolation winding L2 to supply power to a secondary LLC chip (LLC IC, namely an LLC control unit), the LLC chip is started, the main transformer auxiliary winding generates induced voltage to supply power to the PFC chip, and the secondary winding outputs +12V to supply power to the LLC chip. And the PFC chip and the LLC chip work normally, and the power supply system is started.

The power supply starting method provided by the embodiment is suitable for the display device provided by the embodiment, and the standby chip LLC control unit chip is in the secondary side and cannot directly get power from the primary high-voltage wire.

According to the starting method of the power supply, the auxiliary isolation winding is added to the inductor in the PFC unit, so that the auxiliary isolation winding and the inductor in the PFC unit induce voltage to supply power to the chip of the secondary LLC control unit, and the self-starting of the power supply which cannot be started by directly taking power from the primary high-voltage line when the standby chip is on the secondary side is realized.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims

1. The utility model provides a display device, includes the power strip, its characterized in that, be equipped with the LLC unit on the power strip, the LLC unit includes: the device comprises an LLC control unit, an LLC power conversion unit, a voltage feedback signal unit, a current feedback signal unit and a first voltage regulation switch;

the voltage feedback signal unit is respectively connected with an output end of the first output voltage and the LLC control unit; the voltage feedback signal unit is used for feeding back a first output voltage related signal to the LLC control unit; the voltage feedback signal unit includes: two voltage dividing resistors; the input of the voltage feedback signal unit is the first output voltage, and the output is the first output voltage related signal after voltage division;

when the backlight is turned on, the LLC control unit is configured to control a frequency of the LLC power conversion unit according to the output current signal to stabilize the output current, and to control a duty cycle of a driving signal of the first voltage regulation switch according to the first output voltage-related signal to stabilize the first output voltage; when the backlight is turned off, the LLC control unit is further configured to control the frequency of the LLC power conversion unit according to the first output voltage-related signal to stabilize the first output voltage; the first output voltage is a mainboard voltage, and the output current is a current required by the backlight assembly;

2. The display device according to claim 1, wherein the display device further comprises a PFC unit, the LLC power conversion unit comprising: LLC power switches and transformers;

3. The display device according to claim 1, wherein the first voltage adjustment switch is connected in series with an output winding of the first output voltage of the LLC power conversion unit for adjusting the first output voltage.

4. The display device according to claim 1, wherein the LLC control unit further comprises an error operational amplifier and a voltage-controlled oscillator;

5. The display device according to claim 3, wherein the LLC unit further comprises: a second voltage regulating switch;

6. The display device according to claim 1, wherein the current feedback signal unit comprises: a current collection resistor connected in series with the backlight assembly;

the input of the current feedback signal unit is the second output voltage, and the output is the acquired output current signal.

7. The display device according to any one of claims 1 to 6, wherein a PFC unit is further provided on the power board, and the PFC unit includes a PFC inductor, an auxiliary isolation winding, and a PFC control unit; the auxiliary isolation winding is arranged on one side of the PFC inductor; and the auxiliary isolation winding is used for inducing voltage with the PFC inductor to supply power to the LLC control unit.

8. A method for starting a power supply, which is used for the display device according to claim 7, wherein the method comprises: