KR101066093B1 - DC uninterrupted power supply employing bidirectional energy flows - Google Patents

Abstract

The present invention relates to an uninterruptible power supply, and more specifically, to supply power to the load when the commercial power for driving the load is disconnected, and when the commercial power is normally supplied to the load charges the power to the power supply, The present invention relates to an uninterruptible power supply capable of two-way power transmission capable of realizing high power density and low cost by implementing soft switching using leakage reactance of the transformer unit itself.

Uninterruptible Power Supplies, Soft Switching, Resonant Frequency, Leakage Reactance

Description

DC uninterrupted power supply employing bidirectional energy flows}

The present invention relates to an uninterruptible power supply, and more specifically, to supply power to the load when the commercial power for driving the load is disconnected, and when the commercial power is normally supplied to the load charges the power to the power supply, The present invention relates to an uninterruptible power supply capable of two-way power transmission capable of realizing high power density and low cost by implementing soft switching using leakage reactance of the transformer unit itself.

An uninterrupted power supply (UPS) is an auxiliary power supply that supplies voltage to a load in the event of a power failure or breakdown in a system accident.

Due to the recent technology development, most home electric appliances have a built-in rectifier, and therefore, research on DC uninterruptible power supply that does not require a separate inverter device is active.

On the other hand, although the DC uninterruptible power supply can be stabilized through high-speed switching, there is a limitation in increasing the switching frequency due to switching loss and stress, and thus, power is supplied to the load by a hard switching method.

Therefore, there is an urgent need to develop an uninterruptible power supply that can reduce power loss by using soft switching to increase power conversion efficiency.

However, in order to implement soft switching, a separate resonance reactor for resonance must be included inevitably, and thus there is a disadvantage in that the configuration is complicated and the manufacturing cost increases.

The inventors of the present invention can transfer the power charged in the power supply to the load, or charge the commercial power to the power supply, research efforts to develop an uninterruptible power supply that operates in a soft switching method, power transmission in both directions is possible, By using the self leakage reactance of the transformer unit in the resonance, the technical configuration of the uninterruptible power supply that maximizes the power transmission efficiency has been developed to complete the present invention.

Accordingly, it is an object of the present invention to provide an uninterruptible power supply capable of transferring power in both directions to transfer power charged to a power supply to a load or to charge commercial power to the power supply when the commercial power is disconnected.

In addition, another object of the present invention is to provide an uninterruptible power supply that does not require a separate resonance reactor by using the leakage reactance of the transformer unit in the LC resonance.

The objects of the present invention are not limited to the above-mentioned objects, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the present invention is an uninterruptible power supply for supplying power to a load when the commercial power is disconnected, and is connected to a rectifier for rectifying the commercial power to supply direct current power to the load, and is chargeable. And a power supply unit for supplying input DC power, a first switching unit for switching the input DC power to output the following transformer unit when the commercial power is disconnected, or rectifying power input from the following transformer unit to charge the power unit; A second switch for converting an input DC power to output a transformer power, and rectifying the transformer power to supply the load to the load, or switching the DC power output from the rectifier to the transformer to supply the transformer to charge the power supply; The first switching unit and the second switching unit by detecting disconnection of the It provides an uninterruptible power supply comprising: a control unit for.

In a preferred embodiment, the first switching unit is connected in series with each other and connected in parallel to both ends of the power supply unit to divide the input DC power supply, the first capacitor and the second capacitor, one end is connected to one end of the first capacitor And the other end of which is connected to one end of an input side coil of the transformer unit, a first switch for outputting power divided by the first capacitor to the input side coil and one end of which is connected to one end of the second capacitor, and the other end of the input side of the transformer unit. A second switch connected to one end of a coil and outputting power divided by the second capacitor to the input side coil, and the other end of the input side coil is connected between the first capacitor and the second capacitor. .

In a preferred embodiment, the second switch is a third switch, one end of which is connected to one end of the output side coil, a fourth switch of which one end is connected to one end of the third switch, and the other end of the third switch. And a third capacitor connected to the other end of the fourth switch, and a second capacitor connected to the other end of the fourth switch, and the other end of the third capacitor connected to the other end of the third capacitor. It is connected between the end of the fourth capacitor, both ends of the load is connected to one end of the third capacitor and one end of the fourth capacitor.

In a preferred embodiment, the switches each comprise a semiconductor element and a diode connected in anti-parallel to the semiconductor element.

In a preferred embodiment, the control unit alternately 'on' the first switch and the second switch while the third switch and the fourth switch are 'off' when the commercial power is disconnected. The input DC power of the power supply unit is supplied to the load.

In a preferred embodiment, when the commercial power is normally supplied to the load, the control unit alternately turns the third switch and the fourth switch with the first switch and the second switch 'off'. 'ON' to allow the DC power output from the rectifier to be charged to the power supply.

In a preferred embodiment, the control unit controls the switching frequency of each of the switches to be lower than the resonance frequency of the leakage reactance of the transformer unit and the capacitance of each capacitor, so that each switch to the zero current switching operation.

The present invention has the following excellent effects.

First, according to the uninterruptible power supply of the present invention, since the DC power of the rectifier supplying the power of the power supply to the load side or rectifying the commercial power can be charged to the power supply side, power can be received in both directions.

In addition, according to the uninterruptible power supply of the present invention, soft switching is implemented both when the power supply of the power supply unit is supplied to the load or when the DC power supply of the rectifier is charged to the power supply unit. There is an effect that can be raised.

In addition, according to the uninterruptible power supply device of the present invention, the leakage reactance of the transformer itself is used for LC resonance without the need for a separate resonance reactor, so that the manufacturing cost increase due to the addition of passive elements can be reduced, and high power density can be realized.

The terms used in the present invention were selected as general terms as widely used as possible, but in some cases, the terms arbitrarily selected by the applicant are included. In this case, the meanings described or used in the detailed description of the present invention are considered, rather than simply the names of the terms. The meaning should be grasped.

Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Like reference numerals designate like elements throughout the specification.

1 is a view showing an uninterruptible power supply device according to an embodiment of the present invention, Figures 2 and 3 are views for explaining a process of supplying power to the load by the uninterruptible power supply device according to an embodiment of the present invention. 4 and 5 are views for explaining a process of charging power to the power supply unit of the uninterruptible power supply apparatus according to an embodiment of the present invention.

Referring to the drawings, the uninterruptible power supply 100 according to an embodiment of the present invention is the power supply unit 110, the first switching unit 120, the transformer unit 130, the second switching unit 140 and the control unit ( 150).

In addition, the output terminal of the uninterruptible power supply 100 is connected to both ends of the load 30, more specifically, converts the commercial power supply 10 into a direct current power supply, and supplies the converted direct current power to the load 30 It is connected to the output terminal of the rectifier 20.

In addition, the rectifier 20 is provided inside the load 30, for example, a home electric appliance.

That is, the uninterruptible power supply 100 according to the embodiment of the present invention is a DC uninterruptible power supply for outputting DC power.

The power supply unit 110 is rechargeable and the input DC power for operating the load 30 is charged.

In addition, the power supply unit 110 supplies the input DC power to the load 30 when the commercial power supply 10 is disconnected due to system failure or power failure and thus cannot supply power to the load 30.

The first switching unit 120 switches the input DC power to the transformer unit 130 to be described below, or rectifies the power input from the transformer unit 130 to charge the power unit 110. .

That is, when the first switching unit 120 supplies the input DC power to the load 30, the first switching unit 120 operates as an inverter that converts DC into AC, and charges the commercial power 10 to the power unit 110. In this case, it operates as a rectifier for converting AC into DC.

A detailed description will be given with reference to FIGS. 2 to 5.

In addition, the first switching unit 120 is connected in series with each other and connected in parallel to both ends of the power supply unit 110 to divide the input DC power supply, the first capacitor 121 and the second capacitor 122, one end Is connected to one end of the first capacitor 121, and the other end is connected to one end of the input side coil 131 of the transformer unit 130, and the power divided by the first capacitor 121 is transferred to the input side coil 131. The first switch 123 and one end of the output is connected to one end of the second capacitor 122, the other end is connected to one end of the input side coil 131, the divided power to the second capacitor 122 And a second switch 124 output to the input side coil 131.

In addition, the other end of the input side coil 131 is connected between the first capacitor 121 and the second capacitor 122.

That is, the first switching unit 120 is a half-bridge type switching unit that divides the input DC power and supplies the input side coil 131 in both directions.

However, the first switching unit 120 does not divide the input DC power supply, but a push-pull type current that flows in both directions about the center tap of the input side coil 131 using two switching elements. A full-bridge switching unit for connecting a switching unit or four switching elements in a bridge form to allow current to flow in both directions of the input side coil 131 may be used.

In addition, the first switch 123 and the second switch 124 include semiconductor devices 123a and 124a and diodes 123b and 124b connected in reverse parallel to the semiconductor devices 123a and 124a, respectively. Is done.

The transformer unit 130 transforms the power output from the first switching unit 120 to output the transformer power, and includes an input side coil 131 and an output side coil 132.

The second switching unit 140 rectifies the transformer power output from the transformer unit 130 and supplies it to the load 30 or, conversely, switches the DC power output from the rectifier 20 to switch the transformer unit. Supplying to the 130 allows the power supply unit 110 to charge the input DC power.

That is, the second switching unit 140 operates as a rectifier when supplying power to the load 30 and as an inverter when charging the power supply unit 110.

In addition, one end of the second switch 140 is connected to one end of the output coil 132 of the transformer unit 130, and one end of the third switch 141 is connected to one end of the third switch 141. The fourth switch 142 is connected, one end of the third capacitor 143 is connected to the other end of the third switch 141 and one end is connected to the other end of the fourth switch 142, the other end is the third And a fourth capacitor 144 connected to the other end of the capacitor 143.

In addition, the other end of the output coil 132 is connected between the third capacitor 143 and the fourth capacitor 144, one end of the third capacitor 143 and one end of the fourth capacitor ( 144 is connected to both ends of the load 30 to supply power.

In addition, since the third capacitor 143 and the fourth capacitor 144 are connected in series to each other, the third capacitor 143 and the fourth capacitor 144 are connected to each other in series so as to back up the transformed power output from the transformer unit 130 and supply the load 30 to the load 30. There is this.

In addition, the third switch 141 and the fourth switch 142 include semiconductor devices 141a and 142a and diodes 141b and 142b connected in reverse parallel to the semiconductor devices 141a and 142a, respectively. Is done.

The control unit 150 controls the first switching unit 120 or the second switching unit 120 by detecting the disconnection of the commercial power supply 10, the input DC power of the power supply unit 110 is the load It is supplied to 30 or the DC power output from the rectifier 20 to be charged to the power supply unit 110.

Hereinafter, a process of supplying the input DC power of the power supply unit 110 to the load 30 by the uninterruptible power supply device 100 according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3. .

First, the controller 150 'turns on' the first switch 123 in a state of 'off' the third switch 141 and the fourth switch 142.

Next, the first capacitor 121, the semiconductor device 120a of the first switch 123, and the input side coil 131 of the transformer unit 130 form a closed loop, and the first capacitor 121 is closed. The current flows in one direction by the divided power to the input coil 131 of the transformer unit 130.

Next, current is induced in the output coil 132 of the transformer unit 130, and the output coil 132, the diode 141b of the third switch 141, and the third capacitor 143 are closed loops. The third capacitor 143 is charged with a transformer power output from the transformer unit 130 and is supplied to the load 30.

At this time, the uninterruptible power supply device 100 according to an embodiment of the present invention performs LC resonance by the leakage reactance L ₁ of the transformer unit 130 and the capacitance C _s of the third capacitor 143. Done.

In addition, the leakage reactance value may be expressed as a sum of the leakage reactance of the output side coil 122 reduced to the input side and the leakage reactance of the input side coil 121 of the transformer unit 130 as shown in Equation 1 below. .

Here, the L _l1 is the leakage reactance, the L _l2 of the input-side coil 131 is the turns ratio of the leakage reactance, wherein said transformer is a portion 120 of the output-side coil 132.

In addition, the capacitance C _s of the third capacitor 143 is also calculated by reducing to the input side of the transformer unit 120 as shown in Equation 2 below.

Here, a is the turn ratio of the transformer unit 120 and C ₃ is the capacity of the third capacitor 143.

In addition, the resonance frequency f _o is as shown in Equation 3 below.

In addition, when the resonance frequency f _o is greater than the switching frequency of the first switch 123, the current I _{( sw1 )} flowing through the first switch 123 becomes discontinuous, and the first switch ( When 123 is 'on', the current I _{( sw1 )} flowing in the first switch 123 starts to flow, and the current I _{( sw1 )} flowing in the first switch 123 becomes the first switch. Since the resonance is terminated and becomes 0 [A] before the 123 is 'off', the first switch 123 performs the zero current switching operation at both 'on' and 'off'.

Therefore, it is possible to implement soft switching without switching loss without having a separate resonance reactor.

Next, the controller 150 'off' the first switch 123 and 'on' the second switch 124.

Next, the second capacitor 122, the input side coil 131 of the transformer unit 130, and the semiconductor element 124a of the second switch 124 form a closed loop and are connected to the second capacitor 122. The current flows in the other direction to the input side coil 131 of the transformer unit 130 by the divided power.

Next, an induction current is induced in the output coil 132 of the transformer unit 130, and the output coil 132, the diode 142b of the fourth switch 142, and the fourth capacitor 144 are closed. The fourth capacitor 144 is looped and the transformer power output from the transformer unit 130 is charged and supplied to the load 30.

At this time, the uninterruptible power supply device 100 according to an embodiment of the present invention is LC resonance by the leakage reactance (L ₁ ) of the transformer unit 130 and the capacitance of the fourth capacitor (144).

In addition, the switching frequency of the second switch 124 is controlled to be lower than the resonance frequency (f _o ) and the zero current switching operation. In addition, the zero current switching operation of the second switch 124 is the same as the zero current switching operation of the first switch 124 will be omitted.

Next, the controller 150 'off' the second switch 124 and 'on' the first switch 123.

That is, the controller 150 alternately 'on' the first switch 123 and the second switch 124 to operate as a boost converter for boosting the input DC power and the input. DC power supply 110 is supplied to the load (30).

Meanwhile, although the first switch 123 is described as being 'on' first, the second switch 124 may be 'on' first, and the first switch 123 and the second switch 124 may be used. If alternately 'on' may supply the input DC power of the power supply unit 110 to the load (30).

Hereinafter, a process of charging the DC power output from the rectifier 20 to the power supply unit 110 of the uninterruptible power supply device 100 according to an embodiment of the present invention will be described with reference to FIGS. 4 and 5.

First, the controller 150 'turns on' the first switch 123 in a state of 'off' the first switch 123 and the second switch 124.

Next, the third capacitor 143, the semiconductor element 141a of the third switch 141, and the output side coil 132 of the transformer unit 130 form a closed loop, and the output side coil 132 has a closed loop. Current flows due to the voltage of the third capacitor 143.

Next, a current is induced in the input coil 131, the input coil 131, the diode 123b of the first switch 123, and the first capacitor 121 form a closed loop, and the first The power supply unit 110 is charged by the voltage charged in the capacitor 121.

In this case, the controller 150 controls the switching frequency of the third switch 123 to be lower than the resonance frequency caused by the leakage reactance of the transformer 130 and the capacitance of the first capacitor 121 to perform zero current switching. To lose.

In addition, since the zero current switching operation of the third switch 123 is substantially the same as the zero current switching operation of the first switch 123, description thereof will be omitted.

Next, the controller 150 'off' the third switch 141 and 'on' the fourth switch 142 so that the fourth capacitor 143, the output coil 132, and the The semiconductor element 142a of the fourth switch 142 forms a closed loop so that a current flows in the output side coil 132.

Next, a current is induced in the input coil 132, and the input coil 132, the second capacitor 122, and the diode 124b of the second switch 124 form a closed loop to form the second capacitor. Voltage 122 is charged, and the power supply unit 110 is charged.

In addition, the controller 150 controls the switching frequency such that the fourth switch 142 also switches zero current in the same manner as the first switch 142.

That is, the uninterruptible power supply device 100 according to an embodiment of the present invention operates as a buck converter for stepping down voltage when charging the power supply unit 110.

Meanwhile, although the third switch 141 is described as being 'on' first, the fourth switch 142 may be 'on' first, and the third switch 141 and the fourth switch 142 may be used. When alternately 'on', the DC voltage output from the rectifier 20 can be stepped down to charge the power supply 110.

Therefore, since the uninterruptible power supply device 100 according to an embodiment of the present invention may supply the input DC power to the load 30 side or the DC power of the rectifier 20 to the power supply unit 110 side, Power transfer is possible in both directions.

In addition, when switching the input DC power to the load 30 or charging the DC power of the rectifier 20 to the power supply unit 110, all soft switching is realized, so that the transformer efficiency can be greatly increased.

6 is a view showing a waveform of the switching operation of the first and second switches of the uninterruptible power supply according to an embodiment of the present invention, Figure 7 is a third and third of the uninterruptible power supply according to an embodiment of the present invention 4 is a diagram illustrating a switching operation waveform of a fourth switch.

Referring to the drawings, when the uninterruptible power supply 100 according to an embodiment of the present invention transmits the input DC power of the power supply unit 110 to the load 30, the first switch 123 and the first 2 switch 124 is 'on', 'off' when the current (I _{( sw1 )} , I _{( sw2 )} ) flowing through each switch is 0 [A] to perform zero current switching operation (ZCS) It can be seen that.

In addition, when the DC power is charged from the rectifier 20 to the power supply unit 110, the third switch 141 and the fourth switch 142 also have currents I _{( sw3 )} and I _{( sw4 )} ) is 0 [A] 'on', 'off' it can be seen that the zero current switching operation.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

1 is a view showing an uninterruptible power supply device according to an embodiment of the present invention,

2 and 3 are views for explaining a process of supplying power to the load by the uninterruptible power supply device according to an embodiment of the present invention,

4 and 5 are views for explaining a process of charging power to the power supply unit of the uninterruptible power supply apparatus according to an embodiment of the present invention,

6 is a view showing a switching operation waveform of the first and second switches of the uninterruptible power supply according to an embodiment of the present invention,

7 is a view illustrating switching operation waveforms of third and fourth switches of an uninterruptible power supply according to an embodiment of the present invention.

In the drawings according to the present invention, the same reference numerals are used for components having substantially the same configuration and function.

<Description of the symbols for the main parts of the drawings>

100: uninterruptible power supply 110: power supply

120: first switching unit 121: first capacitor

122: second capacitor 123: first switch

124: second switch 130: transformer unit

131: input coil 132: output coil

140: second switch 141: third switch

142: fourth switch 143: third capacitor

144: fourth capacitor 150: control unit

Claims (7)

delete delete An uninterruptible power supply for supplying power to a load when the commercial power is disconnected, and is connected to a rectifier for rectifying the commercial power and supplying DC power to the load. A power supply unit which is chargeable and supplies input DC power; A first switching unit for switching the input DC power to output the following transformer unit when the commercial power is disconnected, or for rectifying the power input from the following transformer unit to charge the power unit; A transformer unit for outputting a transformer power by transforming the input DC power; A second switching unit configured to rectify the transformer power and supply the load to the load, or switch the DC power output from the rectifier to supply the transformer unit to charge the power unit; And And a controller configured to detect disconnection of the commercial power and control the first switching unit and the second switching unit. The first switching unit: First and second capacitors connected in series with each other and connected in parallel to both ends of the power supply unit to divide the input DC power supply; A first switch having one end connected to one end of the first capacitor and the other end connected to one end of an input side coil of the transformer unit, and outputting power divided by the first capacitor to the input side coil; And A second switch having one end connected to one end of the second capacitor and the other end connected to one end of an input side coil of the transformer unit and outputting a voltage divided by the second capacitor to the input side coil. The second switching unit: A third switch having one end connected to one end of an output side coil of the transformer unit; A fourth switch having one end connected to one end of the third switch; A third capacitor having one end connected to the other end of the third switch; And And a fourth capacitor having one end connected to the other end of the fourth switch and the other end connected to the other end of the third capacitor. The other end of the input side coil is connected between the first capacitor and the second capacitor, and the other end of the output side coil is connected between the third capacitor and the fourth capacitor, When the commercial power is normally supplied to the load, the controller boosts the third switch and the fourth switch by alternately turning on the third switch and the fourth switch with the first switch and the second switch turned off. The DC switch output from the rectifier is charged to the power supply unit, and the third switch and the fourth switch are turned off when the commercial power is disconnected. The switch alternately 'on' to operate as a buck converter so that the input DC power of the power supply unit is supplied to the load, and the switching frequency of each of the switches is a resonance frequency caused by leakage reactance of the transformer unit and capacitance of each capacitor. And controlling the lower ones to cause the zero current switching operation of each of the switches. The method of claim 3, wherein And each of said switches comprises a semiconductor device and a diode connected in anti-parallel to said semiconductor device. delete delete The method according to claim 3 or 4, The control unit calculates the resonance frequency by using Equation 3 below. &Quot; (3) &quot;

Here, L ₁ is the leakage reactance, C _s is the capacitance, the leakage reactance is calculated by Equation 1 below, and the capacitance is calculated by Equation 2 below. [Equation 1]

Here, L _l1 is a leakage reactance of the input side coil, L _L2 is a leakage reactance of the output side coil, and a is the turn ratio of the transformer unit. [Equation 2]

Here, a is the turn ratio of the transformer unit, and C is the capacitance of the capacitor to be charged.

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