KR101462812B1 - Power sepply device and control method thereof - Google Patents

Abstract

The present invention relates to a power supply device comprising: an insulated converter unit which includes a switch configured to switch input power, a primary winding configured to receive the input power by the switching of the switch, and a secondary winding configured to electromagnetically connected to the primary winding and to receive the power from the primary winding, wherein a primary region where the switch and the primary winding are positioned and a secondary region where the secondary winding is positioned are insulated from each other; a voltage feedback unit which includes an auxiliary winding electromagnetically connected to the secondary winding, acquires information on an output voltage from the secondary winding, and is positioned in the primary region; an input current information acquiring unit which acquires information on an input current in the primary region; an input voltage information acquiring unit which acquires information on an input voltage; and an output current information acquiring unit which acquires information on an output current based on the information on the output voltage, the input current, the input voltage, wherein the input current information acquiring unit acquires the information on the input current when a certain time passes after.

Description

POWER SEPPLY DEVICE AND CONTROL METHOD THEREOF BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an isolated power supply apparatus of a primary side regulation (PSR) scheme.

Recently, mobile devices such as smart phones and tablet PCs are attracting much attention. Therefore, a lot of research and development on an adapter device for charging the battery of the mobile device is under way. The adapter device must be able to stably supply the output power required by the devices connected thereto. In addition, in order to maximize the portability, the adapter device is required to be reduced in size and weight.

On the other hand, the adapter device has different regulations and power specifications to be satisfied according to the power specifications of each device.

Since there is no power factor and harmonic regulation in the battery charging system of less than 75W class, the present battery charging system has the flyback converter that can configure the circuit with the smallest number of the insulated DC converters It is widely adopted.

However, as standby power regulation has been gradually strengthened, studies on an insulated power supply device of a PSR (Primary Side Regulation) type that indirectly controls the output power from the primary side are being actively researched.

In the secondary side regulation (SSR) system which directly controls the output power from the secondary side, a photocoupler (Photo Coupler) for transmitting the control signal to the primary side and a bias resistor There is a difficulty in satisfying the standby power regulation.

The power supply system of the PSR system is advantageous for satisfying the standby power as compared with the power supply system of the SSR system because the secondary control unit can be omitted. In addition, the PSR type power supply device has a high effect of reducing the number of elements and reducing the volume.

Due to these advantages, there is a growing interest in PSR type power supplies and various studies are underway.

However, the output current predicting method in the conventional PSR type flyback converter can be applied only to DCM (Discontinuous Current Mode) and BCM (Boundary Current Mode) driving. Thus, as the power specifications required by each device are increased, the current stress on the primary and secondary sides increases, and it is difficult to achieve high efficiency due to the current loss.

Therefore, it is required to research and develop a new method for ensuring high efficiency operation in a PSR type power supply device for satisfying standby power regulation.

Korean Patent No. 10-1215074

The present specification provides a method for estimating an output current of a PSR power supply applicable in CCM (Continuous Current Mode).

The power supply apparatus according to an embodiment of the present invention includes a switch for switching an input power source, a primary winding for receiving input power by the switching, and a secondary winding for receiving power from the primary winding by being electromagnetically coupled to the primary winding, An insulated converter unit insulated from the primary side region in which the switch and the primary winding are located and the secondary side region in which the secondary winding is located; A voltage feedback unit having an auxiliary winding electromagnetically coupled with the secondary winding, acquiring output voltage information from the secondary winding, and located in the primary side region; An input current information obtaining unit for obtaining input current information of the primary side region; An input voltage information obtaining unit for obtaining input voltage information of the primary side region; And an output current information obtaining unit for obtaining output current information based on the output voltage information, the input current information, and the input voltage information, wherein the input current information obtaining unit obtains the input current information from the input current information obtaining unit, The input current information can be obtained at a point in time when it elapses.

The input current information obtaining unit may obtain the input current information at a point of time when one half of the time of maintaining the switching on state from the time when the switch is switched on elapses.

The output current information obtaining unit may obtain output current information according to the following equation.

Io = (Vin x Iin) / Vo

Here, Vo denotes output voltage information Vo, Iin denotes input current information, and Vin denotes input voltage information.

The power supply may further include a switch control unit for controlling the switch based on the output current information.

The switch control unit may include a low-pass filter for removing noise of the output current information.

The switch control unit may output the error information by comparing the output current information with predetermined target current information, and may output a switch control signal by comparing the error information with a predetermined triangular wave.

A control method of a power supply apparatus according to an embodiment of the present invention includes a switch, a primary winding, and a secondary winding, wherein a primary side region in which the switch and the primary winding are located and a secondary side region in which the secondary winding is located are insulated Wherein the input current information of the primary side region and the input of the primary side region at a point of time when one half of the time for maintaining the switching on state from the time the switch is switched on elapses, Obtaining voltage information, output voltage information from the secondary winding; Obtaining output current information based on the output voltage information, the input current information, and the input voltage information; And controlling the switch based on the output current information.

The present disclosure can provide a method for estimating the output current of a PSR power supply applicable in CCM (Continuous Current Mode).

1 is a configuration diagram of a flyback DC / DC converter of the PSR type.
2 is a main signal waveform diagram of a flyback DC / DC converter of the PSR type shown in FIG.
3 is a configuration diagram of a flyback DC / DC converter of the PSR type according to an embodiment of the present invention.
4 is a diagram showing a sensing time point of the input current information Iin.
5 is a diagram showing error information ero, a triangular wave Vsaw, a control signal Vgate outputted based thereon, and an input current waveform Ipri.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals are used to designate identical or similar elements, and redundant description thereof will be omitted. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. In addition, it should be noted that the attached drawings are only for easy understanding of the embodiments disclosed in the present specification, and should not be construed as limiting the technical idea disclosed in the present specification by the attached drawings.

On the other hand, for convenience of explanation, the configuration of the power supply apparatus will be described with reference to a flyback converter in this specification.

However, the configuration according to the embodiments described herein may be applied to a forward converter, a half-bridge converter, a full-bridge converter, a push-pull converter, a resonant converter, Will be readily apparent to those skilled in the art.

1 is a configuration diagram of a flyback DC / DC converter of the PSR type.

1, the flyback DC / DC converter of the PSR type controls the internal power switch M ₁ by a PWM (Pulse Width Modulation) method or a PFM (Pulse Frequency Modulation) method to generate a primary voltage Vpri, A flyback driving unit 10 for supplying a primary voltage Vpri from the flyback driving unit 10 to a secondary voltage Vsec according to the turns ratio of the primary winding Np and the secondary winding Ns, A rectifier diode D1 for rectifying the secondary voltage Vsec from the transformer 20 and an output capacitor C1 for smoothing the voltage through the rectifier diode D1, .

The transformer 20 is equivalent to a magnetizing inductor component L _M connected in parallel to the primary winding Np and exhibiting magnetization of a magnetic core, (L _lk ) located on the primary current (I in) path by leakage of the magnetic flux.

The flyback DC / DC converter of the PSR type is provided with an auxiliary winding Nt electromagnetically coupled with the secondary winding Ns. The flywheel DC / And a voltage feedback section 30 for obtaining the voltage information Vt_sen. The voltage feedback unit 30 may include a diode D2 and a capacitor C2.

In addition, the flyback DC / DC converter of the PSR type may include a control unit 40. The control unit 40 may control the switch M ₁ based on the voltage information Vt_sen and the input current information Iin_sen.

The operation of such a PSR type flyback DC / DC converter will be described with reference to FIGS. 1 and 2. FIG.

2 is a main signal waveform diagram of a flyback DC / DC converter of the PSR type shown in FIG.

The average current of the current I _D flowing in the secondary diode D 1 in the flyback converter operating in the DCM is equal to the average of the output current I ₀ supplied to the load. Therefore, the flyback converter can predict the average current of the output diode current and supply an accurate output current to the load.

The input voltage V _IN is applied to the primary winding Np during the _ON time T _ON of the switch M ₁ . At this time, the primary current Iin linearly increases from 0 to the peak value (i _pk ). During this time the energy is applied from the input and stored in the primary winding Np.

When the switch M ₁ is turned off, the secondary diode D 1 is turned on by the energy stored in the primary winding Np. At this time, the diode current I _D linearly decreases from the peak value Ipk x Np / Ns to zero. The energy stored in the secondary winding Ns is transmitted to the load during the on time Toff_1 of the secondary side diode D1. During this period, the sum of the output voltage and the diode voltage drop (VO + VF) Nt / Ns is reflected in the secondary winding.

Therefore, the PSR type flyback DC / DC converter can predict the output current using the primary current Iin and the auxiliary winding voltage Vt.

For example, the average value of the output current can be obtained by the following equation.

(1)

Where I _o is the output current, i _pk is the peak value of the primary side current, Np / Ns is the turns ratio of the primary and secondary windings, Ts is one period of the switching period, T0ff_1 is the ON state of the secondary side diode D2 Time, Rsen is the resistance value connected to the switch of the flyback converter, and Vi_sen is the voltage value measured at Rsen.

The PSR type flyback DC / DC converter can obtain the peak value of the primary side current. In addition, the PSR type flyback DC / DC converter can obtain the on time of the secondary side output diode D1 through the output voltage of the auxiliary winding.

Therefore, the PSR type flyback DC / DC converter can predict the output current I ₀ based on the above equation.

In the case of a flyback converter operating with a DCM, all the energy stored in the magnetizing inductor can be transferred to the secondary side during the on time (Ton) of the switch M1.

However, in the case of a flyback converter operating with CCM, the prediction of output current by the above method is limited.

3 is a configuration diagram of a flyback DC / DC converter of the PSR type according to an embodiment of the present invention.

3, the PSR type flyback DC / DC converter includes an input power source Vin, an insulation converter unit 100, a voltage feedback unit 210, an input current information acquisition unit 220, (230), an output current information obtaining unit (240), and a switch control unit (300).

The input power supply unit (Vin) may provide input power to the insulated converter unit (100).

The insulated converter unit 100 includes a switch SW for switching the input power source, a primary winding N1 for receiving input power by switching, a power source for switching the power source from the primary winding N1 by electromagnetic coupling with the primary winding N1, And a secondary winding N2 receiving the secondary winding N2.

The region where the switch SW and the primary winding N1 are positioned is defined as a primary side region and the region where the secondary winding N2 is located is defined as a secondary side region. The primary side region and the secondary side region may be insulated.

The voltage feedback unit 210 may include an auxiliary winding electromagnetically coupled with the secondary winding N2 to obtain output voltage information Vo from the auxiliary winding. Meanwhile, the voltage feedback unit 210 may be located in the primary side region.

The input current information obtaining unit 220 may obtain the input current information Iin of the primary side region.

The input voltage information obtaining unit 230 may obtain the input voltage information Vin of the primary side region.

Meanwhile, since the energy conservation law is applied between the input power Pin and the output power Po of the insulation converter, the input power Pin and the output power Po satisfy the following relational expression.

(2)

Pin = Po

Here, Pin denotes input power and Po denotes output power.

(3)

Vin × Iin = Vo × Io

Herein, Vin denotes input voltage information, Iin denotes input current information, Vo denotes output voltage information, and Io denotes output current information.

Therefore, the output current information Io can be detected by the following equation.

Io = (Vin x Iin) / Vo

That is, the output current information obtaining unit 240 may obtain the output current information Io based on the output voltage information Vo, the input current information Iin, and the input voltage information Vin.

Hereinafter, a method of detecting the input current information by the input current information obtaining unit 220 will be described.

4 is a diagram showing a sensing time point of the input current information Iin.

4 (a) is a view showing the input current information sensing time point in the converter DCM driving method.

4B is a view showing input current information sensing timing in the converter CCM driving method.

4A and 4B, the input current information obtaining unit 220 senses input current information at a point of time after a predetermined time has passed since the switch SW of the insulation converter unit was switched on.

Specifically, the input current information acquiring unit 220 can sense the input current information at a point of time when one half of the time (Ton) during which the switch SW of the insulated converter unit is switched on from the switching on state is maintained have.

4 (b), the average input current obtained by the input current information obtaining unit 220 is expressed by the following equation.

(4)

Iin = (Ipk + Iini) / 2 (Ton / Ts)

As described above, the method of detecting the input current at the midpoint of the switching on time Ton is applicable to both DCM, BCM, and CCM driving methods. In addition, when the input current is detected by the above method, accurate output current prediction is possible.

In addition, when the controller of the converter unit is designed in a digital manner, the above-described method is advantageous in designing. That is, the input current information acquisition method described above is more suitable for digital control than an analog controller because the input current is detected at the midpoint of the switching on time Ton.

The switch control unit 300 can control the switch SW based on the output current information.

The switch controller 300 may include a low pass filter 310, a first comparator 322, and a second comparator 324.

The low-pass filter 310 can remove noise of the output current information.

The first comparator 322 can output the error information ero by comparing the output current information Io with the predetermined target current information Icom.

The second comparator 324 may compare the error information ero with a predetermined triangular wave Vsaw to output a switch control signal.

5 is a diagram showing error information ero, a triangular wave Vsaw, a control signal Vgate outputted based thereon, and an input current waveform Ipri.

5A shows an example of the error information ero output from the first comparator and an example of the triangle wave Vsaw input to the second comparator.

At this time, the triangular wave Vsaw repeats at a predetermined period Ts and has an isosceles triangle shape.

5 (b) shows an example of the control signal Vgate output based on the error information ero and the triangular wave Vsaw.

5A and 5B, the second comparator sets the switch control signal Vgate to a high level in a section where the error information ero is greater than a predetermined triangular wave Vsaw, and outputs error information ero The switch control signal Vgate can be set to a low level in a section where the voltage Vgate is smaller than the predetermined triangular wave Vsaw to output the switch control signal Vgate.

That is, the greater the difference between the target current information Icom and the output current information Io, the higher the rate of application of the switch control signal Vgate.

5 (c) shows an example of the input current waveform Ipri.

5 (a), (b) and (c), the triangular wave Vsaw is repeated at a predetermined period Ts and is compared with the error information ero in an isosceles triangle shape. Becomes the intermediate point of the ON period of the switch control signal Vgate and the point where the triangular wave Vsaw becomes the lowest becomes the intermediate point of the input current waveform Ipri.

Therefore, the input current information obtaining unit 220 obtains the triangular wave Vsaw information, senses the input current information at the time when the triangular wave Vsaw becomes the lowest, and detects the switching current from the time point when the switch SW is switched on It is possible to detect the input current at the time when 1/2 of the holding time has elapsed.

According to an embodiment of the present invention, the controller 300 generates the switch control signal Vgate at the second time point T (n-1) by input current information obtained at the first time point T (n) Can be used. That is, the control unit 300 detects the primary current in the first period and generates the switch control signal Vgate using the primary current detected in the first period during the second period after the first period, The duty ratio in two cycles can be determined in the first cycle.

According to the above-described method, the PSR type flyback DC / DC converter according to the embodiment of the present invention is also applicable to the CCM driving method.

That is, the output current predicting method in the conventional PSR type flyback converter can be applied only to DCM (Discontinuous Current Mode) and BCM (Boundary Current Mode) driving. Accordingly, as the power specification required by each device is increased, the current stress on the primary and secondary sides increases, and it is difficult to achieve high efficiency due to the current loss. However, the PSR type flyback DC / DC converter according to the embodiment of the present invention can ensure high efficiency operation.

In addition, the flyback converter of the PSR type according to the embodiment of the present invention can be implemented by a simple method since the output current can be accurately predicted in all operating regions by one algorithm in implementing the digital controller.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular forms disclosed. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: Insulation converter section 210: Voltage feedback section
220: input current information acquisition unit 220: input voltage information acquisition unit
240: output current information acquisition unit 300: switch control unit
310: Low-pass filter 322: First comparator
324: second comparator

Claims (7)

A switch for switching an input power source, a primary winding receiving an input power by the switching, and a secondary winding electromagnetically coupled to the primary winding to receive power from the primary winding, wherein the switch and the primary winding An insulation converter unit insulated from a secondary side region where the secondary side winding and the secondary side winding are located;
A voltage feedback unit having an auxiliary winding electromagnetically coupled with the secondary winding and obtaining output voltage information from the auxiliary winding, the voltage feedback unit being located in the primary side region;
An input current information obtaining unit for obtaining input current information of the primary side region;
An input voltage information obtaining unit for obtaining input voltage information of the primary side region; And
An output current information obtaining unit for obtaining output current information based on the output voltage information, the input current information, and the input voltage information;
/ RTI >
Wherein the input current information obtaining unit obtains the input current information at a point of time when a predetermined time has elapsed since the switch was turned on. The apparatus of claim 1, wherein the input current information obtaining unit comprises:
And acquires the input current information at a point of time when 1/2 of the time of maintaining the switching-on state from the time when the switch is switched on elapses. The apparatus according to claim 1, wherein the output current information obtaining unit
A power supply apparatus for obtaining output current information according to the following formula.
Io = (Vin x Iin) / Vo
Here, Vo denotes output voltage information Vo, Iin denotes input current information, and Vin denotes input voltage information. The method according to claim 1,
And a switch control unit for controlling the switch based on the output current information. The apparatus as claimed in claim 4,
And a low-pass filter for removing noise of the output current information. The apparatus as claimed in claim 4,
And outputting a switch control signal by comparing the output current information with predetermined target current information to output error information and comparing the error information with a predetermined triangular wave. A control method of a power supply apparatus including a switch, a primary winding, and a secondary winding, and including an insulation converter unit insulated from a primary side region in which the switch and the primary winding are located and a secondary side region in which the secondary winding is located,
Obtaining input current information of the primary side region, input voltage information of the primary side region, and output voltage information at a point of time when half of the time of maintaining the switching on state from the time when the switch is switched on;
Obtaining output current information based on the output voltage information, the input current information, and the input voltage information; And
And controlling the switch based on the output current information.

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