KR101214254B1 - Bidirectional dc-dc converter - Google Patents

Abstract

The present invention provides a bidirectional DC-DC converter that implements a boosting transformer and a falling transformer as one core.
The bidirectional DC-DC converter according to the present invention includes a magnetic flux generated from an input voltage source for providing a DC power source, a primary winding, a primary winding for exchanging energy with the primary winding, a first boost winding, and a first boost winding. It includes a second boost winding for magnetic flux, the primary winding has one end connected to the first node, the other end connected to the second node, the second winding one end connected to the third node, and the other end Connected between the four nodes, the first booster winding is first connected to the second booster winding, the other end is connected to the primary winding, the second booster winding is first connected to the first booster winding, and the other end is An integrated transformer connected to an input voltage source, a first node and a third node connected to the first node and the second node to change a voltage by applying a predetermined voltage to the first node and the second node, and the voltage of the third node. The voltage of the third node may be transferred to the fifth or sixth node corresponding to the polarity of the fifth node, or the fifth It includes a second switching unit for transmitting the de voltage and the voltage of the sixth node to the one end of the second winding.

Description

Bidirectional DC-DC Converters {BIDIRECTIONAL DC-DC CONVERTER}

The present invention relates to a bidirectional DC-DC converter, and more particularly, to a bidirectional DC-DC converter that can be implemented in a small size.

Electrical devices that use batteries as power sources, such as electric vehicles, require charging devices to charge the batteries. The charger requires a bi-directional DC-DC converter that charges the battery from the power system and supplies the energy stored in the battery to the power system. Korea Patent Publication 10-2011-0029772 is a push-pull method that can be transformed with high efficiency without the need for a separate resonator reactor, and the output side is composed of a back pressure circuit having a simple structure of a transformer for easy implementation and advantageous for high voltage boosting. Soft switching DC / DC converters are presented.

The bidirectional DC-DC converter needs a boosting technique for converting a low voltage of a battery into a high voltage and a technique for converting a high voltage into a low battery charging voltage. In addition, an insulation configuration, such as galvanic isolation, is required between the battery and the power system. Therefore, a transformer is indispensable for implementing the step-up, step-down and galvanic isolation functions. In the bidirectional DC-DC converter, a step-up inductor and a step-down transformer are used to form a step-up and step-down function, thereby increasing the size and cost of the bi-directional DC-DC converter.

The present invention provides a bidirectional DC-DC converter that implements a boosting transformer and a falling transformer as one core.

According to a first aspect of the present invention, an input voltage source for providing a DC power source, a primary winding, a first secondary winding for exchanging energy with a primary winding, a second secondary winding, a first boost winding, and a first boost The magnetic flux generated from the windings includes a second boosting winding in which the magnetic flux is interlinked. The primary winding has one end connected to the first node and the other end connected to the second node, and the first secondary winding has one end. The other end is connected to the second secondary winding, the second secondary winding is connected to the first secondary winding, the other end is connected to the fourth node, and the first boost winding is first 2 is connected to the booster winding, the other end is connected to the primary winding, the second booster winding is connected to the first booster winding, and the other end is connected to the integrated voltage, the first node and the second node The voltage of the third node is connected to the first switching unit and the third node to apply a predetermined voltage to change the voltage of the first node and the second node Bidirectional DC- including a second switching unit for transmitting the voltage of the third node to the fifth node or the sixth node corresponding to the polarity, or the voltage of the fifth node and the voltage of the sixth node to one end of the second winding It is to provide a DC converter.

In addition, the first switching unit is connected between the first switch and the ground and is connected between the first node and the ground and the second node and the switch to perform a switching operation in response to the first switching signal and switching in response to the second switching signal. And a second switch for performing an operation, wherein the first switch is implemented as a transistor, a first switching signal is input to the gate, and a first diode is connected between the source and the drain, and the second switch is implemented as a transistor and is connected to the gate. A bidirectional DC-DC converter in which a second switching signal is input, a second diode is connected between a source and a drain, and the first switch and the second switch are simultaneously turned on in some sections by the first switching signal and the second switching signal. To provide.

Additionally, a third diode connected between the first node and the seventh node and configured to allow a current to flow in the direction from the first node to the seventh node, and between the second node and the seventh node and connected to the second node in the second node. The present invention provides a bidirectional DC-DC converter further comprising a fourth diode for allowing current to flow in a seven node direction, a clamp capacitor connected to the seventh node, and a clamp resistor connected in parallel with the clamp capacitor.

Additionally, the second switching unit is connected between the third node and the fifth node and is connected between the third switch and the third node and the sixth node operating in response to the third switching signal, and corresponding to the fourth switching signal. And a fourth switch that operates, wherein the third switch is connected to the fifth electrode between the first electrode and the second electrode in response to the third switching signal, and the fourth switch is connected to the first electrode in response to the fourth switching signal. The sixth diode is connected between the second electrode, and the third switch and the fourth switch provide a bidirectional DC-DC converter which is turned on at different times.

In addition, the present invention provides a bidirectional DC-DC converter further comprising a first capacitor connected between the fourth node and the fifth node and a second capacitor connected between the fourth node and the sixth node.

Additionally, the integrated transformer includes a center leg, a first leg, and a second leg, wherein the center leg is formed with a primary winding, and the first leg is formed with a first boost winding and a first secondary winding. The second leg provides a bidirectional DC-DC converter in which a second boost winding and a second secondary winding are formed.

In addition, the center leg provides a bidirectional DC-DC converter with air gaps.

In addition, the second switching unit is to provide a bidirectional DC-DC converter for selectively flowing a current in the third winding in response to the voltage formed between the fifth node and the sixth node.

According to the bidirectional DC-DC converter according to the present invention, it is possible to implement a step-up inductor and a transformer by using a single core to implement a small size of the bidirectional DC-DC converter and to reduce the usage of the core, The price can be reduced.

1 is a structural diagram showing an embodiment of a bidirectional DC-DC converter according to the present invention.
FIG. 2 is a structural diagram illustrating a structure of the integrated transformer shown in FIG. 2.
3 is a timing diagram showing waveforms of a bidirectional DC-DC converter in the forward operation.
4 is a timing diagram showing waveforms of a bidirectional DC-DC converter in a reverse operation.

Hereinafter, the present invention will be described in detail so that those skilled in the art can easily understand and reproduce the present invention through these embodiments.

1 is a structural diagram showing an embodiment of a bidirectional DC-DC converter according to the present invention.

Referring to FIG. 1, the bidirectional DC-DC converter 100 includes an input power supply unit 110, a first switch unit 120, an integrated transformer 130, a second switch unit 140, and a clamp unit 150. do.

The input power supply unit 110 supplies a predetermined DC power Vin to the integrated transformer 130. In one embodiment, the input power source 110 may use a battery. The first switch unit 120 includes a first switch M1, a second switch M2, a third diode D3, and a fourth diode D4. The first switch M1 and the second switch M2 may be implemented as MOS transistors. The first switch M1 and the second switch M2 may include a source and a drain gate electrode, and the source electrode may be referred to as a first electrode and a drain electrode as a second electrode. In the first switch M1, the first electrode is connected to the first node N1, the second electrode is connected to the ground, and the gate receives the first switching signal C_Sig1. In the second switch M2, the first electrode is connected to the second node N2, the second electrode is connected to the ground, and the gate receives the second switching signal C_Sig2. In addition, a third diode D3 and a fourth diode D4 are connected to the first electrode and the second electrode of the first switch M1 and the second switch M2, respectively.

The third diode D3 is connected between the first node N1 and the seventh node N7 and is connected such that a current flows in the direction from the first node N1 to the seventh node N7. The fourth diode D4 is connected between the second node N2 and the seventh node N7 and is connected such that current flows from the second node N2 toward the seventh node N7. In one embodiment, the clamp unit 150 is further included, and the clamp unit 150 includes a clamp capacitor CC and a clamp resistor RC. The clamp capacitor CC and the clamp resistor RC are connected to the clamp capacitor CC between the seventh node N7 and the ground, and the clamp resistor RC is connected in parallel with the clamp capacitor CC. The clamp unit 150 causes the surge voltage generated by the switching operation of the first switch M1 and the second switch M2 to be stored in the clamp capacitor CC, and the stored surge voltage is consumed by the clamp resistor RC. To protect the clamp capacitor (CC).

The integrated transformer 130 receives a DC power supply through a first end connected with the first node N1 and the input power supply 110, and a second end connected with the second node N2 and the input power supply 110. In response to the voltage difference between the first node N1 and the DC power source Vin and the voltage difference between the second node N2 and the input power source Vin, energy formed in the primary winding of the integrated transformer 130 may be reduced. Pass it to the secondary winding. In addition, the secondary winding of the integrated transformer 130 is connected to the third node (N3) and the fourth node (N4). The detailed structure of the integrated transformer 130 will be described in detail with reference to FIG. 2 below. The second switch unit 140 includes a third switch Q1 and a fourth switch Q2. The third switch Q1 and the fourth switch Q2 may be implemented as an insulated Gated Bipolar Transistor (IGBT) or a Bipolar Junction Transistor (BJT). When the third switch Q1 and the fourth switch Q2 are implemented as IGBTs, the third switch Q1 and the fourth switch Q2 include a source, a drain, and a gate electrode. When the source is referred to as a first electrode, The drain may be referred to as a second electrode. In addition, when the third switch Q1 and the fourth switch Q2 are implemented as BJTs, the third switch Q1 and the fourth switch Q2 include an emitter, a collector, and a base electrode, and the emitter is configured as a first emitter. When referred to as an electrode, the collector may be referred to as a second electrode. The first electrode of the third switch Q1 is connected to the fifth node N5, the second electrode is connected to the third node N3, and the base or gate receives the third switching signal C_Sig3. In the fourth switch Q2, the first electrode is connected to the fourth node N4, the second electrode is connected to the sixth node N6, and the base or gate receives the fourth switching signal C_Sig4. In addition, the second switch unit 140 is connected between the first capacitor C1 between the fourth node N4 and the fifth node N5, and is formed between the fourth node N4 and the sixth node N6. Two capacitors C2 are connected. In the third switch Q1 and the fourth switch Q2, the fifth diode D5 and the sixth diode D6 are respectively connected between the collector and the emitter or the source and the drain, respectively.

FIG. 2 is a structural diagram illustrating a structure of the integrated transformer illustrated in FIG. 1.

Referring to FIG. 2, the core of the integrated transformer 130 includes a center leg 131a, a first leg 131b, and a second leg 131c. Each leg of the core is arranged in parallel so that the first leg 131b, the center leg 131a, and the second leg 131c are sequentially arranged from top to bottom, and the first leg 131b and the center leg 131a are arranged in order. ), Both ends of the second leg 131c are connected to each other. The center leg 131a and the air gap are formed so that the first boost winding 133a and the second boost winding 133b have appropriate inductance values.

The primary winding 132, which is the primary winding of the integrated transformer, is wound around the center leg 131a. On the left side of the first leg 131b, a first boost winding 133a wound in series with the primary winding 132 is wound, and on the right side, a first secondary winding 134a, which is a secondary winding, is wound. The first boosting winding 133a wound on the first leg 131b and the second boosting winding 133b wound on the second leg 131c are wound in opposite directions. On the right side of the second leg 131c is wound a second boosting winding 133b connected in series to the first boosting winding 133a, and on the left side, a second secondary winding 134b, which is a secondary winding. The first secondary winding wound on the first leg 131b and the second secondary winding wound on the second leg 131c are wound in opposite directions.

Also, the primary winding 132 is formed between the first node N1 and the second node N2, and the second winding 132b is formed between the third node N3 and the fourth node N4. . Then, one end of the first boosting winding 133a is connected to the second boosting winding 133b, the other end is connected to the primary winding 132, and the second boosting winding 133b is one of the first boosting winding. It is connected to the winding 133a and the other end is connected to the input power (Vin).

Since the first boost winding 133b and the second boost winding 133c formed on the first leg 131b are wound in opposite directions, the magnetic flux generated by the first boost winding 133a and the second leg ( The magnetic fluxes generated in the second boost winding 133b formed in 131c cancel each other out of the center leg 131a. Therefore, it does not affect the primary winding 132 formed in the center leg 131a. Since the first secondary winding 134a and the second secondary winding 134b formed in the first leg 131b are wound in opposite directions, the first secondary winding 134a formed in the first leg 131b may not be formed. The generated magnetic flux and the magnetic flux generated in the second secondary winding 134b formed in the second leg 131c cancel each other out.

3 is a timing diagram showing waveforms of a bidirectional DC-DC converter in the forward operation.

Referring to FIG. 3, the first switching signal C_Sig1 and the second switching signal C_Sig2 have a section in which the duty ratio overlaps each other with 0.5 or more. That is, the first switching signal C_Sig1 and the second switching signal C_Sig2 overlap each other in the first section T1, the third section T3, and the fifth section T5. In the first section T1, the first switching signal C_Sig1 and the second switching signal C_Sig2 are input as high signals so that the first switch M1 and the second switch M2 are turned on. When the first switch M1 and the second switch M2 are turned on, the ground is connected to the first node N1 and the second node N2. Therefore, the first voltage Vp1 and the second voltage Vp2 on the primary side of the integrated transformer 130 become the same voltage because they are the difference between the ground and the input voltage Vin. In addition, the direction of the current input to the primary winding 132 by the first voltage Vp1 and the second voltage Vp2 is reversed. As a result, the voltage induced by the first voltage Vp1 and the second voltage Vp2 of the primary winding 132 cancels out. In addition, the voltage induced in the first secondary winding 134a and the second secondary winding 134b is also canceled. In addition, a current increases in the first boosting winding 133a and the second boosting winding 133b by the input voltage Vin.

In the second section T2, the first switching signal C_Sig1 is kept high and the second switching signal C_Sig2 is turned low so that the first switch M1 is turned on and the second switch M2 is turned on. It turns off. When the first switch M1 is turned on and the second switch M2 is turned off, the magnitude of the second voltage Vp2 on the primary side of the integrated transformer 130 is not changed, but the first voltage Vp1 is not changed. The magnitude of λ becomes small corresponding to the voltage of the first node N1 and the voltage of the first voltage Vp1 corresponds to Equation 1 below.

Here, Vi is the voltage of the DC power provided from the input terminal, VL is the voltage across the inductance, Vo is the voltage between the fifth node (N5) and the sixth node (N6), n is the winding ratio.

Accordingly, the magnitudes of the first voltage Vp1 and the second voltage Vp2 on the primary side of the integrated transformer 130 may be different, resulting in a voltage induced by the first voltage Vp1 and the second voltage Vp2. Since the offset does not cancel, a current flows in the secondary second winding 132b of the integrated transformer 130. In this case, the current flowing in the secondary of the integrated transformer 130 is charged in the output capacitor C1 through the fifth diode D5 connected to the third switch Q1.

In the third section T3, the first switching signal C_Sig1 and the second switching signal C_Sig2 are input as high signals so that the first switch M1 and the second switch M2 are turned on. When the first switch M1 and the second switch M2 are turned on, the ground is connected to the first node N1 and the second node N2. Therefore, since the first voltage Vp1 and the second voltage Vp2 formed on the primary side of the integrated transformer 130 correspond to the difference between the ground and the input voltage Vin, they have the same voltage. The direction of the current input to the primary winding 132 by the first voltage Vp1 and the second voltage Vp2 is reversed. Therefore, in the primary winding 132, the voltage induced by the first voltage Vp1 and the second voltage Vp2 is canceled, so that energy is not transferred secondarily. At this time, a current increases in the first boosting winding 133a and the second boosting winding 133b by the input voltage Vin.

In the fourth section T4, the first switching signal C_Sig1 becomes low and the second switching signal C_Sig2 remains high so that the first switch M1 is turned off and the second switch M2 is turned off. Is on. When the second switch M2 is in the ON state, since the second node N2 is connected to the ground, the magnitude of the second voltage Vp1 of the primary side of the integrated transformer 130 is not different from that of the third section T3. However, the magnitude of the second voltage Vp2 becomes smaller corresponding to the voltage of the second node N2 and corresponds to Equation 2 below.

Here, Vi is the voltage of the DC power provided from the input terminal, VL is the voltage across the inductance, Vo is the voltage between the fifth node (N5) and the sixth node (N6), n is the winding ratio.

Therefore, the magnitudes of the first voltage Vp1 and the second voltage Vp2 on the primary side of the integrated transformer 130 may be different from each other, and thus the primary winding may be formed by the first voltage Vp1 and the second voltage Vp2. Since the voltage induced at 132 is not canceled, the primary winding 132 and the second winding 132b exchange energy, thereby causing a current to flow in the second winding 132b. At this time, since the current flowing in the second winding 132b is opposite in polarity to the current flowing in the second section T2, the output second capacitor C2 is output through the sixth diode D6 connected to the fourth switch Q2. ) Is charged. In the output terminal Vo, the charged voltage is transferred to the first capacitor C1 and the second capacitor C2. In this case, when the third switch Q1 and the fourth switch Q2 of the second switching unit 140 perform the on / off operation in synchronization with the fifth diode D5 and the sixth diode D6, respectively. That is, when the current is stored in the first capacitor C1 through the fifth diode D5, the third switch Q1 is turned on so that the current is transferred from the third node N3 to the fifth node N5. When the current is stored in the second capacitor C2 through the sixth diode D6, the fourth switch Q2 is turned on so that the current is transferred from the third node N3 to the sixth node N6. The conduction loss due to the current stored in the first capacitor C1 and the second capacitor C2 can be reduced.

4 is a timing diagram showing waveforms of a bidirectional DC-DC converter in a reverse operation.

Referring to FIG. 4, the third switch Q1 and the fourth switch Q2 are operated by the third switching signal C_Sig3 and the fourth switching signal C_Sig4. The duty ratio of the third switching signal C_Sig3 and the fourth switching signal C_Sig4 is 0.5 or less so that the third switch Q1 and the fourth switch Q2 are not turned on at the same time. In addition, the first switch M1 and the second switch M2 formed on the primary side of the integrated transformer 130 may maintain an off state. However, when the first switch M1 and the second switch M2 of the first switching unit 120 perform on / off operations in synchronization with the first diode D1 and the second diode D2, respectively, That is, when a current flows through the first diode D1, the first switch M1 is turned on so that the current is transferred from the third node N3 to the fifth node N5, and the sixth diode D6. When the current is stored in the second capacitor (C2) through to turn on the fourth switch (Q2) so that the current is transferred from the third node (N3) to the sixth node (N6), the first capacitor (C1) and The conduction loss due to the current stored in the second capacitor C2 can be reduced.

When the third switching signal C_Sig3 is high and the fourth switching signal C_Sig4 is low in the first section T1, the third switch Q1 is turned on and the fourth switch Q2 is turned off. Becomes When the third switch Q1 is on and the fourth switch Q2 is off, current flows in the first secondary winding 134a and the second secondary winding 134b of the integrated transformer 130. Energy is transferred to the primary winding 132 that is the primary winding of the integrated transformer 130. Therefore, a current flows in the primary winding 132 formed in the center leg 131a of the integrated transformer 130, so that the current flows to the input power Vin side.

In the second section T2, the third switching signal C_Sig3 and the fourth switching signal C_Sig4 are turned low, and the third switch Q1 and the fourth switch Q2 are turned off. When the third switch Q1 and the fourth switch Q2 are turned off, current does not flow in the integrated transformer 130. Therefore, the second winding 132b, which is the secondary winding formed on the center leg 131a, prevents current from flowing. When no current flows in the second winding 132b, the second winding 132b is formed with an electromotive force in a direction in which the current can flow again. As a result, the primary winding 132 formed in the center leg 131a of the integrated transformer 130 may flow in the same direction as the first section T1 by the electromotive force formed in the second winding 132b. However, the amount of current flowing over time decreases.

In the third section T3, the third switching signal C_Sig3 is turned low, the fourth switching signal C_Sig4 is turned high, and the third switch Q1 is turned off, and the fourth switch Q2 is turned on. It becomes a state. When the third switch Q1 is turned off and the fourth switch Q2 is turned on, the voltage formed on the second winding 132b formed on the center leg 131a of the integrated transformer 130 is controlled by the first section ( A voltage of opposite polarity to T1) (herein, the first section T1 is a positive voltage and the third section T3 is a-voltage) is formed, which is formed at the center leg 131a of the integrated transformer 130. Current flows through the primary winding 132 that is the primary winding, and the current flows toward the input power supply unit 110.

In the fourth section T4, the third switching signal C_Sig3 and the fourth switching signal C_Sig4 are turned low, and the third switch Q1 and the fourth switch Q2 are turned off. When the third switch Q1 and the fourth switch Q2 are turned off, current does not flow in the second winding 132b that is the secondary winding of the integrated transformer 130. At this time, when the current does not flow in the second winding 132b formed in the center leg 131a, the electromotive force is formed in the direction in which the current can flow again. As a result, the primary winding 132 formed in the center leg 131a of the integrated transformer 130 flows in the same direction as the third section T3 by the electromotive force formed in the second winding 132b. However, the amount of current flowing over time decreases.

It is to be understood that the technical spirit of the present invention has been specifically described in accordance with the preferred embodiments thereof, but it is to be understood that the above-described embodiments are intended to be illustrative and not restrictive. In addition, it will be understood by those of ordinary skill in the art that various embodiments are possible within the scope of the technical idea of the present invention.

100: bidirectional DC-DC converter 110: input power supply
120: first switching unit 130: integrated transformer
140: second switching unit 150: clamp unit

Claims (8)

An input voltage source for providing a DC power source;
Primary winding, first secondary winding exchanging energy with primary winding, second secondary winding, first boost winding, first boost winding The first winding has one end connected to the first node and the other end connected to the second node. The first secondary winding has one end connected to the third node and the other end connected to the second secondary winding. The second secondary winding has one end connected to the first secondary winding, the other end connected to the fourth node, the first boosting winding once connected to the second boosting winding, and the other end connected to the primary winding. An integrated transformer having a second boosting winding connected at one end to a first boosting winding and at another end to an input voltage source;
A first switch connected between the first node and ground and performing a switching operation in response to the first switching signal to change a voltage of the first node, and connected between the second node and ground and corresponding to the second switching signal A first switching unit including a second switch to change a voltage of the second node by performing a switching operation; And
A third switch connected between the third node and the fifth node to transfer the voltage of the third node to the fifth node or the voltage of the fifth node to one end of the second winding in response to the polarity of the voltage of the third node; And a third node connected between the third node and the sixth node to transfer the voltage of the third node to the sixth node or the voltage of the sixth node to one end of the second winding in response to the polarity of the voltage of the third node. A second switching unit including four switches;
Bidirectional DC-DC converter comprising a. The method of claim 1,
The first switch of the first switching unit is implemented as a transistor, the first switching signal is input to the gate and the first diode is connected between the source and the drain,
The second switch is implemented as a transistor, the second switching signal is input to the gate and the second diode is connected between the source and the drain,
A bidirectional DC-DC converter in which a first switch and a second switch are simultaneously turned on in some sections by a first switching signal and a second switching signal. The method of claim 2,
A third diode connected between the first node and the seventh node to allow a current to flow in the direction from the first node to the seventh node, and a second diode connected between the second node and the seventh node in the direction of the second node to the seventh node. A bidirectional DC-DC converter further comprising a fourth diode for allowing current to flow, a clamp capacitor connected to the seventh node, and a clamp resistor connected in parallel with the clamp capacitor. The method of claim 1,
The third switch and the fourth switch of the second switching unit is turned on at different times of the bidirectional DC-DC converter. 5. The method of claim 4,
A bidirectional DC-DC converter further comprising a first capacitor connected between the fourth node and the fifth node and a second capacitor connected between the fourth node and the sixth node. The method of claim 1,
The integrated transformer includes a center leg, a first leg, and a second leg, wherein the center leg has a primary winding, a first leg has a first boost winding and a first secondary winding, and a second leg has a first leg. A bidirectional DC-DC converter in which a booster winding and a second secondary winding are formed. The method according to claim 6,
The center leg is a bidirectional DC-DC converter with air gaps. The method of claim 1,
The second switching unit is a bi-directional DC-DC converter for allowing a current to flow selectively in the third winding in response to the voltage formed between the fifth node and the sixth node.

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