WO2021225318A1

WO2021225318A1 - Electronic device, and control method therefor

Info

Publication number: WO2021225318A1
Application number: PCT/KR2021/005223
Authority: WO
Inventors: 윤영남; 최용호; 김영수; 최진영
Original assignee: 삼성전자(주)
Priority date: 2020-05-08
Filing date: 2021-04-26
Publication date: 2021-11-11
Also published as: KR20210136576A

Abstract

An electronic device comprises: a first switching unit that converts rectified input power into AC power; a transforming unit that transforms and transfers the AC power; an output unit that outputs a DC output voltage on the basis of an output of the transforming unit; a power factor correcting unit that includes a charging element and a second switching unit connected to the transforming unit; and a control unit that controls the first switching unit to adjust the output voltage output by the output unit, and controls the second switching unit such that energy transferred through the transforming unit is charged to the charging element, and the energy charged in the charging element is discharged so as to increase the energy transferred to the output unit through the transforming unit.

Description

Electronic device and its control method

The present invention relates to an electronic device having a power supply for supplying operating energy based on AC power transmitted from the outside and a control method therefor, and more particularly, a power factor correction function in a conversion circuit that converts AC power in the power supply to DC power. It relates to the implemented electronic device and its control method.

In order to calculate and process predetermined information according to a specific process, an electronic device that basically includes electronic components such as a CPU, a chipset, and a memory for arithmetic operation may be of various types depending on the information to be processed or the purpose of use. can be divided into For example, an electronic device includes an information processing device such as a PC or server that processes general-purpose information, an image processing device that processes image data, a display device that displays the processed image data as an image on a screen, and an audio processing device. There are audio devices and household appliances that perform chores in the home. Whatever kind of device is, the electronic device has a power supply that provides electrical energy for operation based on an external AC power supply. The power supply unit may be embedded in the electronic device or provided to be connected to the electronic device in the form of an adapter.

Power factor is one of the many things to be considered in the circuit design of the power supply. The power factor represents the ratio of how little reactive power is supplied to the power supply but not delivered to the load and consumed as compared to the active power used in the load by being actually delivered to the load from the power supply. The power supply part having a poor power factor means that the electric energy delivered to the load is relatively small compared to the electric energy supplied from the outside. Accordingly, a design of a power factor correction function for improving the power factor by reducing reactive power may be applied to the power supply unit.

Various structures have been proposed to implement the power factor correction function in the power supply unit. However, since the conventional structure of the power factor correction function relatively uses many circuit components such as a coil, there are problems in that the volume of the power supply is large, heat is increased, and the material cost is increased.

Therefore, a structure capable of implementing a power factor correction function in the power supply unit, but relatively reducing the volume of the power supply unit, reducing heat generation, and reducing material cost may be required.

An electronic device according to an embodiment of the present invention includes a first switching unit that converts rectified input power into AC power, a transformer that transforms and transmits the AC power, and a DC output voltage based on the output of the transformer. A power factor correcting unit including an output unit for outputting a , a charging element connected to the transformer and a second switching unit, and controlling the first switching unit to adjust the output voltage output by the output unit, through the transformer It may include a controller for controlling the second switching unit so that the transferred energy is charged in the charging element, the energy charged in the charging element is discharged to increase the energy transferred to the output unit through the transforming unit.

Also, the controller may control the current transmitted through the transformer to charge the charging device, and discharge energy charged in the charging device to increase the voltage transmitted through the transformer.

In addition, the second switching unit includes a switching element provided to be open and closed between the charging element and the transformer, and the control unit is configured to add the energy charged to the charging element to the energy transmitted through the transformer. The switching element can be controlled.

In addition, the control unit may turn on the switching element in response to the time when the first switching unit operates so that the direction of the current flowing through the transformer is switched.

In addition, the controller increases the duty ratio of the signal for controlling the switching operation of the first switching element in a section where the magnitude of the input AC voltage is small and decreases it in the section where the magnitude of the input AC voltage is large. can

In addition, the power factor correction unit may further include a diode disposed between the transformer and the output unit, and the control unit may increase the energy transferred to the output unit through the transformer to flow through the diode. .

In addition, the power factor correction unit may further include a capacitor charged based on the energy transmitted to the output unit through the transformer, and provided to transmit the charged electric energy to the output unit.

In addition, it may further include a resonance coil unit charged based on the energy transferred through the transformer and the energy charged in the charging device, the charged electric energy is transmitted through the diode.

In addition, the charging device may include a capacitor.

In addition, the first switching unit may include a plurality of switches, and the control unit may control the direction of the current delivered to the transformer to change by individually opening and closing the plurality of switches.

In addition, the energy transferred through the transformer may be electrical energy transferred from the input coil of the transformer to the output coil.

In addition, the method for controlling an electronic device according to an embodiment of the present invention comprises the steps of converting the rectified input power into AC power by a first switching unit, and a power factor correction unit including a charging element and a second switching unit. , the steps of charging the charging element based on the energy transmitted through the transformer, and controlling the second switching unit to discharge the energy charged in the charging element to increase the energy transferred to the output unit through the transformer. include

1 is an exemplary diagram of an electronic device.

2 is a block diagram of an image processing device of an electronic apparatus.

3 is a block diagram of the AC-DC converter of the power supply unit.

4 is an exemplary diagram illustrating a circuit structure of the AC-DC converter of FIG. 3 .

5 is a graph showing signal waveforms in each part of the AC-DC converter.

6 is a circuit diagram illustrating an operation of an AC-DC converter in a time period T0 to T1 of the time period of FIG. 5 .

7 is a main circuit diagram illustrating an operation of an AC-DC converter in a time period of T1 to T2 among the time period of FIG. 5 .

8 is a main circuit diagram illustrating an operation of an AC-DC converter in a time period of T2 to T3 among the time period of FIG. 5 .

9 is a graph illustrating an example of a time ratio according to a signal transmitted by the power factor control unit to the switching element M5 and an output terminal load.

10 is a graph showing the simulation results of the phases of the input current and the input voltage in the AC-DC converter according to the related art to which the switching device M5 of the present embodiment is not applied.

11 is a graph showing simulation results of input current and input voltage phase due to a power factor correction operation of the switching device M5 according to the present embodiment.

12 is an exemplary diagram of an AC-DC converter circuit in which a design of a switching unit is changed.

13 is an exemplary diagram of a circuit of an AC-DC converter in which the design of the transformer is changed.

14 is a flowchart of an operation in which the control unit controls the AC-DC converter.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. The embodiments described with reference to the drawings are not mutually exclusive unless otherwise stated, and a plurality of embodiments may be selectively combined and implemented in one device. A combination of a plurality of these embodiments may be arbitrarily selected and applied by a person skilled in the art in implementing the spirit of the present invention.

If, in the embodiment, there is a term including an ordinal number such as a first component, a second component, etc., these terms are used to describe various components, and the term distinguishes one component from another component. As used herein, these components are not limited in meaning by terms. Terms used in the embodiments are applied to describe the embodiments, and do not limit the spirit of the present invention.

In addition, when the expression “at least one” among a plurality of components in the present specification appears, this expression refers not only to all of the plurality of components, but also each one or these excluding the rest of the plurality of components. refers to any combination of

1 is an exemplary diagram of an electronic device.

As shown in FIG. 1 , the electronic device 1 according to the present embodiment is implemented as a display device 1 . However, the display device 1 is only one example of the electronic devices 1 that can be implemented, and the electronic device can be implemented as various types of devices such as information processing devices, household appliances, and image processing devices operated by an external power source. can In addition, the electronic device 1 has a screen 201 for displaying an image by processing an image signal, and is implemented as, for example, a TV. However, the electronic device 1 may be implemented as various types of devices other than the TV, for example, a fixed display device including a TV, a monitor, a digital signage, an electronic blackboard, and an electronic picture frame; or an image processing apparatus including a set-top box, an optical media player, and the like; It is an information processing device including a computer body or the like; or a mobile device including a smart phone, a tablet device, and the like; It may be implemented in various types of devices, such as wearable devices.

The electronic apparatus 1 includes an image processing device 100 that processes an image signal based on image content received from the outside or stored therein, and a display unit that displays an image based on an image signal output from the image processing device 100 . (200). In this embodiment, the electronic apparatus 1 in the case where the image processing device 100 is in the form of a media box separated from the display unit 200 is described, but the image processing device 100 and the display unit 200 are one The electronic device 1 coupled to the frame or accommodated in one housing is also possible.

The image processing device 100 receives an image signal according to various transmission methods, such as through short-distance communication with an external device such as a PC or a set-top box, through wide-area network communication with a server, or receiving a broadcast signal in an RF format. do. Alternatively, the image processing device 100 may acquire an image signal by reading image content data stored in an internal storage. The image processing device 100 performs image-related processing such as decoding and scaling on the obtained image signal, and outputs the image-related processing to the display unit 200 . A signal transmission method between the image processing device 100 and the display unit 200 may be both wired and wireless.

The display unit 200 forms a screen 201 for displaying an image signal from the image processing device 100 as an image. The display unit 200 includes a display panel, and various design methods may be applied to the structure of the display panel. The display unit 200 according to the present embodiment is provided in a structure in which a single large screen 201 is formed by a plurality of display panels or a plurality of display modules having a self-luminous structure such as micro LED or OLED. Alternatively, the display unit 200 may be provided in the structure of a single display panel provided with a light-receiving structure such as a liquid crystal method or a self-luminous structure such as an OLED method.

Hereinafter, the configuration of the electronic device 1 will be described.

2 is a block diagram of an image processing device of an electronic apparatus.

As shown in FIG. 2 , the image processing device 100 of the electronic apparatus may include an interface unit 110 . The interface unit 110 includes an interface circuit for the image processing device 100 to communicate with various types of external devices or servers, and to transmit and receive data. The interface unit 110 includes one or more wired interface units 111 for wired communication connection and one or more wireless interface units 112 for wireless communication connection according to a connection method.

The wired interface unit 111 includes a connector or port to which a cable of a predefined transmission standard is connected. For example, the wired interface unit 111 includes a port to which a terrestrial or satellite broadcasting antenna is connected to receive a broadcast signal, or a cable for cable broadcasting is connected. Alternatively, the wired interface unit 111 includes ports to which cables of various wired transmission standards such as HDMI, DP, DVI, Component, Composite, S-Video, and Thunderbolt are connected to be connected to various image processing devices. Alternatively, the wired interface unit 111 includes a USB standard port for connecting to a USB device. Alternatively, the wired interface unit 111 includes an optical port to which an optical cable is connected. Alternatively, the wired interface unit 111 includes an audio input port to which an external microphone is connected, and an audio output port to which a headset, earphone, external speaker, and the like are connected. Alternatively, the wired interface unit 111 includes an Ethernet port connected to a gateway, a router, a hub, or the like to access a wide area network.

The wireless interface unit 112 includes a bidirectional communication circuit including at least one of components such as a communication module and a communication chip corresponding to various types of wireless communication protocols. For example, the wireless interface unit 112 includes a Wi-Fi communication chip that performs wireless communication with an AP (Access Point) according to a Wi-Fi method, Bluetooth, Zigbee, Z-Wave, WirelessHD, WiGig, NFC, etc. It includes a communication chip for performing wireless communication, an IR module for IR communication, and a mobile communication chip for performing mobile communication with a mobile device.

The image processing device 100 may include a user input unit 120 . The user input unit 120 includes various types of user input interface related circuits that are provided to allow a user to manipulate the user to perform a user input. The user input unit 120 may be configured in various forms depending on the type of the image processing device 100 , for example, a mechanical or electronic button unit of the image processing device 100 , a touch pad, a sensor, a camera, and a touch screen. , and a remote controller separated from the image processing device 100 .

The image processing device 100 may include a storage unit 130 . The storage unit 130 stores digitized data. The storage unit 130 has a non-volatile property that can preserve data regardless of whether or not power is provided, and data to be processed by the processor 150 is loaded, and data is stored when power is not provided. It includes memory of volatile properties that cannot. Storage includes flash-memory, hard-disc drive (HDD), solid-state drive (SSD), read-only memory (ROM), etc., and memory includes buffer and random access memory (RAM). etc.

The image processing device 100 may include a power supply unit 140 . The power supply unit 140 delivers power required for operation to each component. For example, the power supply unit 140 converts AC power input from an external power source into DC power, and outputs electric energy adjusted to a current or voltage suitable for each component of the image processing device 100 . As one of the circuit configurations for this purpose, the power supply unit 140 may include an AC-DC converter circuit for converting AC into DC, which will be described later.

The image processing device 100 may include a processor 150 . The processor 150 includes one or more hardware processors implemented with a CPU, a chipset, a buffer, a circuit, etc. mounted on a printed circuit board, and may be implemented as a system on chip (SOC) depending on a design method. When the electronic device is implemented as a display device, the processor 150 includes modules corresponding to various processes such as a demultiplexer, a decoder, a scaler, an audio digital signal processor (DSP), and an amplifier. Here, some or all of these modules may be implemented as SOC. For example, a module related to image processing such as a demultiplexer, a decoder, and a scaler may be implemented as an image processing SOC, and an audio DSP may be implemented as a chipset separate from the SOC.

Hereinafter, the AC-DC converter circuit of the power supply unit 140 will be described.

3 is a block diagram of the AC-DC converter of the power supply unit.

As shown in FIG. 3 , the AC-DC converter 1000 of the power supply receives AC power and outputs DC power. The AC-DC converter 1000 may have various circuit structures according to a design method. In this embodiment, the CLL circuit structure is applied. In a CLL circuit, "C" refers to a capacitor that charges and discharges a voltage, and "L" refers to an inductor that charges and discharges a current. However, the AC-DC converter 1000 is not limited to a CLL circuit structure, and may have an LLC circuit structure depending on a design method.

AC-DC converter 1000 having a CLL circuit structure according to this embodiment is an EMI filter 1100, a rectifier 1200, a switching unit 1300, a resonance capacitor 1400, It includes a transformer 1500 , a resonance coil unit 1600 , a power factor correction unit 1700 , and an output unit 1800 . For convenience, with reference to the transformer 1500 , the front end of the transformer 1500 is referred to as an input side or a primary side, and the rear end of the transformer 1500 is referred to as an output side or a secondary side. Also, the AC-DC converter 1000 includes a controller 1900 that controls the switching unit 1300 and/or the power factor correcting unit 1700 according to a feedback signal input from the output unit 1800 .

The EMI filter 1100 filters or blocks various noises mixed in the frequency of the input electrical energy. In general, AC power supplied from the outside is mixed with electrical noise due to various reasons such as power lines. The EMI filter 1100 removes such noise in the initial stage of processing the electrical energy in the AC-DC converter 1000 .

The rectifier 1200 converts the input AC power into full-wave or half-wave rectified power, and operates so that the current flows in one direction. As the capacitance of the capacitor C1 increases, the power factor decreases, and as the capacitance decreases, the power ripple due to the input frequency appears at the output terminal. The rectifying unit 1200 converts AC input power into full-wave or half-wave power to perform the power factor correction function of the AC-DC converter 1000 .

The switching unit 1300 converts the rectified power output from the rectifying unit 1200 back into AC. The switching unit 1300 includes a plurality of switches, and through individual switching operations of each switch, the direction of the current transmitted through the switching unit 1300 is switched.

The resonance capacitor 1400 charges electric energy transferred through the switching unit 1300 .

The transformer 1500 transforms the input electrical energy and outputs it. The transformer 1500 may include, for example, a transformer.

The resonance coil unit 1600 charges electric energy transferred from the input side to the output side of the AC-DC converter 1000 through the transformer 1500 .

The power factor correction unit 1700 is provided between the transformer 1500 and the output unit 1800 and performs a rectification function together with a function of improving the power factor of the AC-DC converter 1000, thereby providing a direct current to the output unit 1800. Power can be output. Since the power factor correction unit 1700 has a voltage multiplier structure, the number of turns of the output-side coil of the transformer 1500 and thus the number of turns of the resonance coil unit 1600 can be designed to a smaller value. For example, if the power factor correction unit 1700 is not used as a voltage multiplier structure, the turns ratio of the transformer 1500 is 1:2 and the resonance coil unit 1600 is designed to be 4 times the power of 2 to achieve the voltage multiplier. Should be. On the other hand, if the power factor correction unit 1700 has a voltage multiplier structure, the turns ratio of the transformer 1500 may be 1:1 and the resonance coil unit 1600 may be designed to be 1 times.

The output unit 1800 includes components such as a capacitor and is connected to a load to transmit electrical energy output from the power factor correction unit 1700 to the load.

The controller 1900 controls the overall operation of the AC-DC converter 1000 . The controller 1900 may be implemented as a processor 150 (refer to FIG. 2 ), or may be a separate component provided in the AC-DC converter 1000 . The control unit 1900 is implemented as a hardware chipset provided with a microprocessor, a microcontroller, or the like. The control unit 1900 includes a switching control unit 1910 for controlling the switching unit 1300 and a power factor correction unit 1700 for controlling the power factor correcting unit 1700 . However, it is not necessary that the control unit 1900 is divided into a plurality according to roles, and a single control unit 1900 may be provided to control a plurality of components together depending on a design method.

The controller 1900 receives a feedback signal from some components of the AC-DC converter 1000 and also transmits a control signal to each component based on the received feedback signal. For example, the control unit 1900 receives a feedback signal regarding the voltage and current of the input power from the rectifier 1200 and a feedback signal regarding the output voltage from the output unit 1800 . Also, the control unit 1900 outputs a control signal for controlling the operations of the switching unit 1300 and the power factor correcting unit 1700 based on the feedback signal. These control signals are provided to control the switching operation of the switches provided in the switching unit 1300 and the power factor correcting unit 1700, respectively, and specific details will be described later in relation to the circuit structure of the AC-DC converter 1000 .

Hereinafter, the operation of the control unit 1900 according to an embodiment of the present invention will be described.

The control unit 1900 controls the switching unit 1300 so that the output power of the output unit 1800 with respect to the load becomes a target value. The controller 1900 controls the switching operation of the switching unit 1300 so that the output voltage becomes a preset target value based on information on the output voltage fed back from the output unit 1800 .

The control unit 1900 charges the charging element connected to the transformer 1500 based on the output of the transformer 1500 . Here, the charging element is a component provided in the power factor correction unit 1700 , and is provided to charge or discharge electric energy output from the transformer 1500 . A detailed description of the charging device will be described later.

The control unit 1900 controls the power factor correction unit 1700 so that the output of the charged charging element is added to the output of the transformer 1500 and transmitted to the output unit 1800 .

By repeatedly performing these operations, the controller 1900 may achieve a power factor improvement function in the AC-DC converter 1000 with a simpler structure, and reduce the volume and heat generation of the AC-DC converter 1000 .

Meanwhile, the components of the AC-DC converter 1000 controlled by the controller 1900 may be implemented based on various circuit designs. Hereinafter, an example of the circuit structure of the AC-DC converter 1000 according to the present embodiment will be described.

As shown in FIG. 4 , the AC-DC converter 1000 is implemented as a circuit using various components and wiring. The circuit structure shown in this figure is only one of various design methods of the AC-DC converter 1000 . Hereinafter, the circuit of each component will be described.

The rectifier 1200 includes a plurality of diodes, and performs full wave rectification on the input AC power. In addition, the rectifying unit 1200 has a capacitor C1. Capacitor C1 has a small capacitance of several μF to maintain the shape of the full-wave rectified voltage.

The switching unit 1300 includes a plurality of switching elements. In the present embodiment, the switching unit 1300 includes four switching elements M1, M2, M3, and M4 arranged in a full bridge form, but the configuration of the switching unit 1300 is not limited only to the example of this embodiment. Depending on the design method, the switching unit 1300 may include two switching elements arranged in the form of a half-bridge.

The reason why the switching unit 1300 includes a plurality of switching elements is to change the direction of a current applied to an input-side coil of the transformer 1500, which will be described later. That is, the switching unit 1300 may change the direction of the current applied to the transformer 1500 by selectively opening and closing the four switching elements M1, M2, M3, and M4.

The transformer 1500 includes an input-side coil and an output-side coil insulated from each other. The resonance capacitor Cr is connected in series to the input coil of the transformer 1500 , and the magnetizing inductor Lm is connected in parallel to the input coil of the transformer 1500 . The transformer 1500 preferably has a high degree of coupling between the input-side coil and the output-side coil, thereby minimizing leakage inductance.

The resonance coil unit 1600 includes an inductor Ls. When the magnetizing inductor Lm is designed to utilize the transformer's own inductance, the resonant coil unit 1600 is arranged to be connected in series to the output side coil as in the present embodiment. Depending on the design method, the resonant coil unit 1600 may be disposed between the magnetizing inductor Lm and the input side coil of the transformer 1500 . Depending on whether the resonance coil unit 1600 is disposed on the input side or the output side, the inductance setting is necessary in consideration of the turn ratio. For example, if 200 μH is required when the resonant coil unit 1600 is disposed on the input side, an inductance design proportional to the square of (N2/N1) is required when the resonant coil unit 1600 is disposed on the output side. Here, NP is the number of windings of the input-side coil of the transformer 1500 , and NS is the number of windings of the output-side coil of the transformer 1500 .

The power factor correction unit 1700 includes a diode D1, a switching device M5, and capacitors C2 and C3. The node N1 is one end of the output side coil of the transformer 1500 , and the node N2 is the other end of the output side coil of the transformer 1500 . An inductor Ls is disposed between the node N1 and the transformer 1500 . The front end of the diode D1 is connected to one end of the inductor Ls at the node N1. The diode D1 and the switching device D5 are connected in parallel with the inductor Ls at the node N1. Capacitors C2 and C3 are connected in parallel with the output coil of the transformer 1600 at the node N2.

The diode D1 performs a rectification function in the power factor correction unit 1700 . Due to the characteristics of the diode, when the voltage applied to the node N1 is higher than the voltage applied to the output unit 1800 , electric energy may flow from the front end to the rear end of the diode D1 . No electric energy flows from the rear end of the diode D1 to the front end. In addition, when the voltage applied to the node N1 is lower than the voltage applied to the output unit 1800 , electric energy does not flow from the front end to the rear end of the diode D1 . Depending on the design method, the diode D1 may be replaced with a switching device. In this case, the controller 1900 is provided to control the replaced switching device.

The capacitor C3 serves as a charging device in the power factor correction unit 1700 . The capacitor C3 charges or discharges electrical energy according to the direction of the current flowing in the output coil of the transformer 1500 and the condition of the turn-on/turn-off state of the switching element M5.

The capacitor C2 charges electric energy from the output coil of the transformer 1500 and transfers it to the output unit 1800 , and forms a path through which a current flows to the output coil of the transformer 1500 during charging. Capacitor C2 thereby inhibits capacitor C3 from discharging during this period. Depending on the design method, a structure in which the capacitor C2 is omitted is also possible.

The control unit 1900 receives the feedback of the input voltage V_in and the input current I_in from the rectifying unit 1200 , and receives the feedback of the output voltage Vdc_out from the output unit 1800 . Based on this feedback, the controller 1900 controls the switching elements M1, M2, M3, and M4 of the switching unit 1300 and the power factor correction switching element of the power factor correction unit 1700 (hereinafter simply referred to as a switching element) M5 of Each of the switching operations is controlled. A specific control operation of the control unit 1900 will be described later.

Hereinafter, the operation of the AC-DC converter 1000 according to the direction of the current flowing in the input-side coil of the transformer 1500 and the condition of the turn-on/turn-off state of the switching element M5 will be described.

5 is a graph showing signal waveforms in each part of the AC-DC converter.

4 and 5 , the controller 1900 alternately switches the combination of the switching elements M1 and M4 and the combination of the switching elements M2 and M3 over time. The switching elements M2 and M3 are turned off in the time period from T0 to T3 when the switching elements M1 and M4 are turned on, and the switching elements M2 and M3 are turned on in the time period from T3 to T0 when the switching elements M1 and M4 are turned off. do.

The direction of the current flowing through the input-side coil of the transformer 1500 is changed by the control of these switching elements. However, the direction of the current does not change immediately when the switching elements M1 and M4 are turned on and M2 and M3 are turned off, or when the switching elements M1 and M4 are turned off and M2 and M3 are turned on. Due to the presence of the inductors Lm, Ls, and the like, the direction of the current is changed after the lapse of a predetermined time, not when the switching element is turned on/off. An inductor is a component that charges and discharges current. Therefore, even if the current is controlled to change from the first direction to the second direction in the circuit, the inductor serves to cause the inertia of the current to continuously flow in the first direction for a predetermined time.

I _Cr represents the current of the capacitor Cr, V _Cr represents the voltage of the capacitor Cr, and I _Lm represents the current of the inductor Lm, respectively. In particular, the waveform of the current indicates the direction of the current. For example, in a region where the current is (+) and a region where the current is (-), the direction of the current is opposite to each other.

If you look at the control of the switching element and the waveform of the current, you can see how the direction of the current changes. For example, when the switching elements M1 and M4 are turned on and M2 and M3 are turned off at the time point T0, I _Cr does not change directly from the (-) region to the (+) region at the time point T0, but the curve of _{I Cr is (-} ) to the (+) area. From the time T1 when the current passes through 0, the _{direction of I Cr} is completely changed. Conversely, the switching elements M1 and M4 is turned off at the time point T3, and M2 and M3 are turned on, the curve (+) zone in the I _Cr (-) fall toward the region, and, I _Cr is from T4 time point passing through the 0 I _Cr direction is completely changed.

The control unit 1900 turns on the switching device M5 from time point T0 to time T2 and turns it off during the remaining time period. Depending on the design method, the control unit 1900 may turn on the switching device M5 at a time preceding the time point T0, specifically, at a time point between the time points T4 and T0. That is, at the turn-on time of the switching element M5, the direction of the current of the inductor Ls is the direction of the transformer 1500 after the drain-source voltage of the switching element M5 becomes 0 in the section in which the current flows in the inductor Ls in the direction toward the diode D1. It only needs to be performed before changing the direction toward the output side coil. Since a zero voltage switching operation (ZVS) of the switching element M5 is possible, a load during operation of the switching element M5 can be reduced.

Hereinafter, the operation of the circuit for each time period will be described.

As shown in FIGS. 4 and 6 , the AC-DC converter 1000 operates to charge the capacitor C3 with electrical energy during the time period from time T0 to T1 (refer to FIG. 5 ).

At time point T0, M1 and M4 of the switching elements are turned on, M2 and M3 are turned off, and M5 is turned on. Even when the switching elements M1 and M4 are turned on, the inertia through which the current flows in the time period T4 to T0 before T0 continues to act due to the inductor Ls. Accordingly, a current in the first direction (counterclockwise in the drawing) flows in the output coil Lsm of the transformer, and correspondingly, current also flows in the input coil of the transformer in the first direction.

At this time, since the switching element M5 is turned on, the electric energy flowing through the output-side coil Lsm of the transformer is charged in the capacitor C3. Depending on the design method, the switching device M5 may have the parasitic diode D2. In this case, the current flows through the parasitic diode D2 regardless of whether the switching device M5 is turned on or off. However, in order to reduce the load on the parasitic diode D2, the switching device M5 is turned on at the time T0 to allow a current to flow.

Meanwhile, since the voltage at the node N1, which is the front end of the diode D1 performing the rectification function, is lower than the rear end of the diode D1, no current flows from the front end to the rear end of the diode D1.

As shown in FIGS. 4 and 7 , during the time period of time T1 to T2 (see FIG. 5 ), the AC-DC converter 1000 is charged with electrical energy transferred from the input side of the transformer to the output side coil Lsm and the capacitor C3. It operates to charge electrical energy into the inductor Ls.

After the switching elements M1 and M4 are turned on at the time T0, as the time point T1 passes, the inertia of the current flow in the first direction (counterclockwise in the drawing) is overcome by the current flowing in the second direction (clockwise in the drawing) do. Accordingly, after the time point T1, the current in the second direction flows through the input coil of the transformer, and correspondingly, the current in the second direction also flows through the output coil Lsm of the transformer.

At this time, the electric energy charged in the capacitor C3 is discharged from the capacitor C3. The sum of the electrical energy transferred from the input side of the transformer to the output side coil Lsm plus the electrical energy from the capacitor C3 is charged in the inductor Ls.

On the other hand, since the voltage at the node N1, which is the front end of the diode D1, is still lower than the downstream end of the diode D1, no current flows from the front end to the rear end of the diode D1.

As shown in FIG. 8 , during the time period of time T2 to T3 (see FIG. 5 ), the AC-DC converter 1000 uses the electric energy transferred from the input side of the transformer to the output coil Lsm and the electric energy charged in the inductor Ls. Passes the sum to the output.

A current flows in the second direction (clockwise in the drawing) in the input coil of the transformer, and correspondingly, current also flows in the output coil Lsm of the transformer in the second direction. Here, when the switching device M5 is turned off at the time T2, the electric energy charged in the inductor Ls is released, and the voltage at the node N1 increases relatively significantly compared to the rear end of the diode D1. For this reason, the condition that electric energy can be transferred from the front end to the rear end of the diode D1 is satisfied. Therefore, the sum of the electric energy transferred from the input side of the transformer to the output coil Lsm and the electric energy charged in the inductor Ls passes through the diode D1. transmitted to the output.

On the other hand, the diode C2 provides a path for directing the electrical energy flowing to the output unit to the output-side coil Lsm of the transformer. Depending on the design method, a configuration in which only the wiring is connected without the diode C2 is also possible. However, if the diode C2 is not present, since electric energy is emitted from the diode C3 in the current time period, the efficiency may be reduced.

Meanwhile, in the period between time points T3 to T4 in FIG. 5 , the direction of the input current is changed by turning on the switching elements M2 and M3 and turning off the M1 and M4. However, due to the inertial action of the current by the inductor, the operation of the circuit in this time period maintains the shape of FIG. 8 .

In the section between the time points T4 to T0 when the inertia of the current is overcome, the operation of the circuit is shown in the form of FIG. 6 .

The AC-DC converter has a circuit combining a rectifying function and a power factor correction function on the output side, and by repeating such an operation cycle, the power factor can be improved with a simple structure. In the embodiment of the present invention, the flow of current transmitted to the output side occurs even in a section in which the input voltage is lower than the output voltage, thereby improving the power factor in the circuit.

As described in the above embodiment, the control unit 1900 (refer to FIG. 3 ) performs constant voltage output and power factor improvement by a control signal transmitted to each switching element. The switching control unit 1910 (refer to FIG. 3) receives the output voltage from the output unit 1800 (refer to FIG. 3) as feedback, and the duty ratio and operating frequency of the control signal transmitted to the switching unit 1300 (refer to FIG. 3) adjust the The power factor control unit 1920 (refer to FIG. 3) controls the output voltage Vdc_out, the input voltage V_in, and the control signal supplied to the switching element M5 based on the value of the current I_in flowing between the input capacitor C1 and the switching unit. Adjust the fertilization ratio.

The operating frequency of the control signal transmitted to the switching element M5 is synchronized with the operating frequency of the switching unit. The turn-off time of the switching element M5 is, during the period of time T1 to T2 (refer to FIG. 4), sufficient time for the energy accumulated in the inductor Ls to be transferred to the capacitor C2, but before the switching elements M1 and M4 are turned off is carried out Since the switching operation by the switching element M5 transfers the accumulated energy to the output side together with the energy transferred from the input side, it affects not only the power factor improvement function but also the voltage gain of the circuit. Accordingly, the switching operation by the switching device M5 can compensate for insufficient voltage gain when designing a resonance type circuit at, for example, 90 to 264 Vrms input.

Hereinafter, an example in which the power factor control unit controls the control signal will be described.

As shown in FIG. 9, the graph showing the waveform change of the input voltage and input current and the graph showing the time ratio of the control signal to the switching element M5 of the power factor control unit 1920 (refer to FIG. 3) are matched over time have.

I_in denotes an input current that flows when power consumption is relatively high in the load, and I_in' denotes an input current that flows when power consumption is relatively low in the load. In this embodiment, the time ratio of the switching device M5 that enables power factor improvement increases in the section where the magnitude of the input AC voltage is small and decreases in the section where the magnitude of the input AC voltage is large, so that a downwardly concave parabolic curve is formed. have In addition, the concave degree of the parabola changes according to the state of the load and the output voltage.

Among the two curves representing the fertility ratio in this graph, a solid line indicates a case corresponding to I_in, and a dotted line indicates a case corresponding to I_in'. In general, the higher the input voltage and the smaller the load, the higher the output voltage, and the lower the input voltage and the larger the load, the lower the output voltage. For this reason, the concavity of the parabola varies depending on the load condition. In addition, with respect to the output voltage, when the output voltage is low, the total ratio of the fertilization ratio is changed in an increasing direction, and when the output voltage is high, the total ratio of the fertilization ratio is changed in a direction to decrease. In this graph, 25% of the time ratio is an example, and according to a design method, the power factor control unit may control the switching operation of the switching element M5 based on various values of the time ratio.

Hereinafter, comparison of simulation results between the related art and the embodiment of the present invention will be described.

As shown in FIG. 10 , in the AC-DC converter according to the related art, several feedback signals may be obtained through simulation, and a graph of these feedback signals may be shown. Here, the AC-DC converter according to the related art corresponds to a case in which a rectifier circuit including only a diode is applied to the output side without applying the switching device M5 as in the present embodiment.

The first graph relates to the output voltage V_out, and the second graph relates to the input current I_in and the input voltage V_in. The second graph shows the result of dividing the input voltage by 10 to fit the scale. The third graph relates to a voltage (V_Lm) applied to the input side of the transformer and a voltage (V_Sm) applied to the output side of the transformer. The fourth graph relates to the current (I(Ls)) flowing through the inductor Ls on the output side.

The section where electric energy is delivered to the load is the section where V_Lm is higher than V_Sm. In this graph, since there are relatively few sections in which I_in is greater than 0 as a whole, the sections in which electrical energy is actually delivered to the load are relatively small. In addition, in order to improve the power factor, the difference between I_in and V_in should be relatively small, and the phase difference between the two is large. Although the effect of improving the power factor can be seen to some extent by increasing the amplitude of V_Lm, it is expected that the effect of improving the power factor will decrease due to the phase difference between current and voltage in the related technology.

Compared to these related technologies, the case of the embodiment of the present invention is as follows.

11 , in the AC-DC converter according to the present embodiment, each feedback signal according to the switching operation of the switching element M5 may be obtained through simulation, and a graph of these feedback signals may be shown. The meaning of each graph is applied mutatis mutandis to the case of FIG. 10 above.

In the present embodiment, a curve of I_in may be derived as shown in the second graph through full-wave rectification by the rectifying unit 1200 (refer to FIG. 3) and the switching unit 1300 (refer to FIG. 3). Here, if the capacitance of the capacitor C1 (refer to FIG. 4) is designed to be low, the curve of V_in of this graph maintains a shape evenly distributed for each section.

In the present embodiment, unlike the case of the related art, a section in which I_In is greater than 0 is relatively increased, and accordingly, a section in which V_Lm is larger than V_Sm also increases. That is, in this embodiment, since the section in which the electric energy is transmitted to the load is increased compared to the case of the related art, the electric energy transfer efficiency is increased. In addition, in the present embodiment, the phase difference between the current and the voltage is relatively reduced by strengthening the voltage under the control of the switching element M5. As a result, the present embodiment can improve the power factor compared to the case of the related art.

Hereinafter, an example of an AC-DC converter circuit designed to be different from that of the previous embodiment will be described.

As shown in FIG. 12 , the AC-DC converter 2000 includes an EMI filter 2100 , a rectifier 2200 , a switching unit 2300 , a resonance capacitor 2400 , a transformer 2500 , and a resonance coil part 2600 . ), a power factor correction unit 2700 , and an output unit 2800 . In the AC-DC converter 2000 according to the present embodiment, the remaining components except for the switching unit 2300 have the same circuit structure as the components of the same name in the previous embodiment (refer to FIG. 4 ), so these A description will be omitted.

In the switching unit 2300 according to the present embodiment, two switching elements M1 and M2 are provided in the form of a half-bridge. The switching elements M1 and M2 are connected in parallel to the rectifying unit 2200, the resonance capacitor 2400 is connected to a node connecting one end of the switching element M1 and one end of M2, and the other end of each of the switching elements M2 is a transformer It is connected to the other end of the input side coil of 2500.

By switching between the operation of turning on the switching element M1 and turning off M2, and the operation of turning off the switching element M1 and turning on M2, the direction of the current flowing in the input-side coil of the transformer 2500 is changed.

As shown in FIG. 13 , the AC-DC converter 3000 includes an EMI filter 3100 , a rectifier 3200 , a switching unit 3300 , a resonance capacitor 3400 , a transformer 3500 , and a resonance coil part 3600 . ), a power factor correction unit 3700 , and an output unit 3800 . In the AC-DC converter 3000 according to the present embodiment, the remaining components except for the transformer 3500 and the resonance coil 3600 are the same as the components of the same name in the previous embodiment (refer to FIG. 4 ). Since it has a circuit structure, description is abbreviate|omitted about these.

The transformer 3500 according to the present embodiment has a structure in which the inductor Ls, which is the resonance coil unit 3600 , is disposed between the input-side coil of the transformer 3500 and the inductor Lm. Since the inductor Ls is disposed on the input side, the output coil of the transformer 3500 plays a role in emitting the electric energy transferred from the input coil of the transformer 3500, and the electric energy transferred from the input coil is emitted from the capacitor C3. It also serves to transfer electrical energy to the diode D1. That is, after the electric energy charged in the capacitor C3 is released, it is transferred to the primary side by the transformer 3500 and charged in the inductor Ls.

The arrangement of the transformer 3500 and the resonant coil unit 3600 is a structure in which the resonant coil unit 1600 is located at the rear end of the transformer 1500 as shown in FIG. 4 according to the requirements of the AC-DC converter 3000, Alternatively, it may be implemented as a structure in which the resonance coil unit 3600 is located in the transformer 3500 as shown in FIG. 13, and either of them may perform a power factor improvement function.

Hereinafter, in the electronic device according to an embodiment of the present invention, an operation of the control unit of the power supply unit controlling the AC-DC converter will be described.

As shown in FIG. 14 , the following operation is performed by the power supply unit or the control unit of the AC-DC converter.

In step 4100, the control unit converts the input power rectified by the switching unit into AC power so that the output voltage to the load becomes a target value.

In step 4200, the control unit charges the charging device by the power factor correction unit based on the AC power transformed by the transformer unit.

In step 4300, the control unit controls the AC power transformed by the transformer to be transferred to the load by adding the power of the charged charging device to the AC power.

Methods according to an exemplary embodiment of the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer-readable medium. Such computer-readable media may include program instructions, data files, data structures, etc. alone or in combination. For example, a computer-readable medium, whether removable or rewritable, may be a non-volatile storage device, such as a USB memory device, or memory, such as, for example, RAM, ROM, flash memory, memory chips, integrated circuits, or For example, it may be stored in an optically or magnetically recordable storage medium such as a CD, DVD, magnetic disk, or magnetic tape, and at the same time, a machine (eg, computer) readable storage medium. It will be appreciated that a memory that may be included in a mobile terminal is an example of a machine-readable storage medium suitable for storing a program or programs including instructions for implementing embodiments of the present invention. The program instructions recorded in the present storage medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software. Alternatively, the computer program instructions may be implemented by a computer program product.

Claims

In an electronic device,

A first switching unit for converting the rectified input power into AC power;

a transformer that transforms and transmits the AC power;

an output unit for outputting a direct current output voltage based on the output of the transformer;

a power factor correction unit including a charging element connected to the transformer and a second switching unit;

controlling the first switching unit to adjust the output voltage output by the output unit;

A control unit for controlling the second switching unit so that the energy transferred through the transformer is charged to the charging element, and the energy transferred to the output unit through the transformer increases by discharging the energy charged in the charging element electronics.
According to claim 1,

The control unit controls the current transmitted through the transformer to charge the charging element, and the electronic device discharges energy charged in the charging element to increase the voltage transmitted through the transformer.
According to claim 1,

The second switching unit includes a switching element provided so as to be able to open and close between the charging element and the transformer,

The control unit may control the switching element so that energy charged in the charging element is added to the energy transferred through the transformer.
4. The method of claim 3,

The control unit may turn on the switching element in response to a time when the first switching unit operates so that the direction of the current flowing through the transformer is switched.
4. The method of claim 3,

The control unit is an electronic device for increasing a duty ratio of a signal for controlling a switching operation of the first switching element in a section in which the magnitude of the input AC voltage is small and decreasing in a section in which the magnitude of the input AC voltage is large. .
4. The method of claim 3,

The power factor correction unit further includes a diode disposed between the transformer and the output unit,

The control unit may increase the energy transferred to the output unit through the transformer to flow through the diode.
7. The method of claim 6,

The power factor correction unit may further include a capacitor charged based on energy transmitted to the output unit through the transformer, and configured to transmit the charged electric energy to the output unit.
7. The method of claim 6,

The electronic device further comprising a resonance coil unit charged based on the energy transferred through the transformer and the energy charged in the charging element, and provided to transmit the charged electric energy through the diode.
According to claim 1,

The charging element is an electronic device including a capacitor.
According to claim 1,

The first switching unit includes a plurality of switches,

The control unit may individually open and close the plurality of switches, thereby controlling the direction of the current delivered to the transformer to change.
According to claim 1,

The energy transferred through the transformer is electrical energy transferred from an input coil of the transformer to an output coil of the transformer.
In the control method of an electronic device,

converting the rectified input power into AC power by the first switching unit;

Charging the charging element based on the energy transferred through the transformer by the power factor correction unit including the charging element and the second switching unit;

and controlling the second switching unit to discharge the energy charged in the charging element to increase the energy transferred to the output unit through the transformer.
13. The method of claim 12,

A control method of an electronic device for charging the charging element by controlling the current transmitted through the transformer, and discharging the energy charged in the charging element to increase the voltage transmitted through the transformer.
13. The method of claim 12,

The second switching unit includes a switching element provided so as to be able to open and close between the charging element and the transformer,

A control method of an electronic device for controlling the switching element so that the energy charged in the charging element is added to the energy transferred through the transformer.
15. The method of claim 14,

A control method of an electronic device of turning on the switching element in response to a time when the first switching unit operates so that the direction of the current flowing through the transformer is switched.