WO2017065350A1

WO2017065350A1 - Dc/dc converter having coupling inductor and snubber circuit

Info

Publication number: WO2017065350A1
Application number: PCT/KR2015/013718
Authority: WO
Inventors: 이동향
Original assignee: 월드탑텍(주)
Priority date: 2015-10-13
Filing date: 2015-12-15
Publication date: 2017-04-20
Also published as: KR20170043275A; KR101759258B1

Abstract

The present invention relates to a DC/DC converter and, specifically, to a DC/DC converter having a coupling inductor and a snubber circuit, wherein the converter comprises: a coupling inductor installed in parallel to an inductor of a filter unit; a transformer to which an inverse voltage is applied using a voltage applied to the coupling inductor, to minimize a circulating current section and thus minimize a conduction loss; and a snubber circuit installed to the coupling inductor to absorb or discharge a surge voltage generated by the coupling inductor, so as to decrease a surge voltage applied to a diode and thus enable use of a diode having a low voltage rating.

Description

DC / DC Converter with Coupled Inductor and Snubber Circuit

The present invention relates to a DC / DC converter, and in particular, a couple inductor is installed in parallel to the inductor of the filter unit, and a voltage applied to the couple inductor is applied to the transformer unit with a reverse voltage to minimize the circulating current section to minimize the conduction loss. DC with coupled inductor and snubber circuit that installs a snubber circuit in the coupled inductor to absorb and discharge the surge voltage generated from the coupled inductor, thereby reducing the surge voltage applied to the diode so that the diode voltage rating is lowered. It relates to a / DC converter.

In order to supply energy to electronic circuits that require relatively high voltages, they must be boosted to high voltages for use in applications in conjunction with the grid. In addition, some electronic circuits need to be stepped down to a low voltage using a high voltage. One of various step-down and step-up converters for this purpose is a DC / DC converter.

On the other hand, EV (Electric Vehicle) is a futuristic convergence technology that is attracting attention not only from international organizations, but also from governments and companies around the world, with the basis of the global green growth policy.

The electric vehicle receives electric energy from the outside and charges the battery, and then obtains mechanical power by using a voltage charged in the battery. A vehicle charger is a device that provides the voltage required for an electric vehicle to charge low and high voltages, and requires a DC / DC converter that can supply a wide voltage range of DC power from the DC input power to the output using a single output circuit. do.

For example, as shown in FIG. 1, the DC / DC converter 10 includes a switching unit 11 including a plurality of switching elements S1 to S8 to alternately switch a DC input power Vin to apply current. When the current applied according to the switching operation of the switching unit 11 is applied to the primary winding, the bridge rectifier circuit is formed by the transformer unit 12 which is induced in the secondary winding and outputs AC power and the diodes D5 to D8. The rectifier 15 is formed of a rectifier 13 for outputting an output voltage by rectifying the AC power output from the secondary winding side of the transformer unit 12 with a DC power source, an inductor Lo, and a capacitor Co. It consists of a filter unit 14 for filtering the output voltage of the. In this case, between the DC input power Vin and the switching unit 11, input capacitors C1 and C2 are provided to be connected to the DC input power Vin to divide the power, and the switching unit 11 includes a circulating diode ( D1 to D4) are provided.

As shown in FIG. 2, in the DC / DC converter 10, the switching unit 11 is alternately arranged so that the circulating current section is long in the switching elements S2, S7, S3, and S6 during switching, so that the switching elements S2, S7, There is a problem that the conduction loss of S3 and S6 is large.

In addition, the high voltage is applied to the diode of the rectifier at the high voltage output, the diode voltage rating should be used as a large, high voltage breakdown diode has a problem that the loss occurs because the large VF (forward drop voltage).

(Patent Document 1) Korea Patent Registration No. 10-1548528

(Patent Document 2) Korea Patent Registration No. 10-0799856

The present invention is to solve the above problems, install a couple inductor in parallel to the inductor of the pulsar portion, by applying a reverse voltage to the transformer to the voltage applied to the couple inductor to minimize the circulating current section to minimize the conduction loss It is an object of the present invention to provide a DC / DC converter having a couple inductor and a snubber circuit.

In addition, the present invention provides a couple inductor and snubber circuit to install a snubber circuit in the couple inductor to absorb and discharge the surge voltage generated from the couple inductor to reduce the surge voltage applied to the diode to use a low diode voltage rating Another object is to provide a DC / DC converter having a.

Features of the present invention for achieving the above object,

A switching unit including a plurality of switching elements S1 to S8 to alternately switch the DC input power Vin to apply a current; and a secondary winding when a current applied according to the switching operation of the switching unit is applied to the primary winding. A rectifying unit configured to output an AC voltage by converting an AC power outputted from the transformer unit and a diode rectifying circuit formed by diodes D5 to D8 to rectify the AC power output from the secondary winding side of the transformer unit into a DC power source. And a filter unit comprising an inductor (Lo) and a capacitor (Co), the filter unit filtering the output voltage of the rectifier unit, wherein the transformer is connected in parallel between the inductor (Lo) of the filter unit and the rectifier unit. A couple inductor unit applying a reverse voltage to a negative secondary winding to minimize a circulating current section to minimize conduction loss; And a snubber circuit connected in parallel between the couple inductor unit and the rectifier unit to absorb and discharge a surge voltage generated from the couple inductor unit.

Here, the couple inductor unit is coupled to the couple inductor (L1), the circulating diode (Df) in series in the forward direction to the rear end of the couple inductor (L1) to apply a voltage.

Here, the snubber circuit may include a capacitor Csn having one end connected between the couple inductor L1 and the circulating diode Df, and the other end connected between the inductor Lo and the rectifier of the filter part; A resistor Rsn connected between the couple inductor L1 and a capacitor Csn; And a diode Dsn having an anode connected to the capacitor Csn and a cathode connected between the inductor Lo and the rectifier of the filter unit.

Here, the switching unit is any one selected from a half bridge, a full bridge, a three-level half bridge, and a three-level full bridge.

According to the DC / DC converter having a couple inductor and a snubber circuit of the present invention configured as described above, a couple inductor is installed in parallel with the inductor of the filter unit, and a circulating current is applied by applying a reverse voltage to the transformer unit with a voltage applied to the couple inductor. Conduction losses can be minimized by minimizing the intervals.

In addition, according to the present invention, a snubber circuit may be installed in the couple inductor to absorb and discharge the surge voltage generated from the couple inductor, thereby reducing the surge voltage applied to the diode, thereby using a low diode voltage rating.

1 is a circuit diagram illustrating a general three-level full bridge DC / DC converter.

FIG. 2 is a graph for explaining the operation of FIG. 1.

3 is a circuit diagram illustrating a DC / DC converter having a couple inductor and a snubber circuit according to the present invention.

4 is a graph illustrating an operation in a state in which a snubber circuit is removed from a DC / DC converter including a couple inductor and a snubber circuit according to the present invention.

5 is a graph illustrating an operation of a DC / DC converter having a couple inductor and a snubber circuit according to the present invention.

Hereinafter, a configuration of a DC / DC converter having a couple inductor and a snubber circuit according to the present invention will be described in detail with reference to the accompanying drawings.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

Referring to FIG. 3, a DC / DC converter 10 having a couple inductor and a snubber circuit according to the present invention includes a switching unit 110, a transformer unit 120, a rectifying unit 130, and a filter unit. 140, a couple inductor unit 150, and a snubber circuit 160.

First, the switching unit 110 includes first to eighth switching elements S1 to S8 to alternately switch the DC input power Vin to apply a current. Here, the switching unit 110 is applied to any one selected from the half bridge, full bridge, three-level half bridge, three-level full bridge, Figure 3 shows a three-level full bridge for example. In addition, the switching unit 110 is provided with input capacitors C1 and C2 to halve the DC input power Vin, and the first to fourth circulating diodes D1 to 4 between the switching elements S1 to S8, respectively. The first to fourth circulation diodes D1 to 4 are electrically connected to the input capacitors C1 and C2. In addition, the first to eighth switching elements S1 to S8 are preferably MOSFETs.

When the current applied according to the switching operation of the switching unit 110 is applied to the primary winding, the transformer 120 is induced in the secondary winding and outputs AC power.

In addition, the rectifying unit 130 rectifies the AC power output from the secondary winding side of the transformer unit 120 with a DC power source and outputs an output voltage. In this case, the rectifier 130 is connected to both ends of the secondary winding of the transformer 120 in the forward direction, respectively, the fifth diode D5 and the sixth diode D6, and both ends of the secondary winding of the transformer 120. A bridge rectifier circuit composed of a seventh diode D7 and an eighth diode D8 connected in reverse directions, respectively.

Subsequently, the filter unit 140 includes an inductor Lo and a capacitor Co to filter the output voltage of the rectifier 130.

In addition, the couple inductor 150 is connected in parallel between the inductor Lo and the rectifier 130 of the filter unit 140 to apply a reverse voltage to the secondary winding of the transformer unit 120 to minimize the circulating current section. A coupling inductor L1 for minimizing conduction loss and a circulating diode Df are connected in series to the rear end of the coupler inductor L1 in a forward direction to apply a voltage to the couple inductor L1.

In addition, the snubber circuit 160 is connected in parallel between the couple inductor L1 of the couple inductor 150 and the rectifier 130 to absorb the surge voltage generated from the circulating diode Df of the couple inductor 150. And discharge. Here, the snubber circuit 160 has one end connected between the couple inductor L1 and the circulating diode Df, and the other end connected between the inductor Lo and the rectifier 130 of the filter unit 140. An anode is connected to Csn, a resistor Rsn and a capacitor Csn connected between the couple inductor L1 and the capacitor Csn, and the inductor Lo and the rectifier 130 of the filter unit 140 are connected. It is made of a diode (Dsn) is connected to the cathode between.

Hereinafter, an operation of a DC / DC converter having a couple inductor and a snubber circuit according to the present invention will be described in detail with reference to the accompanying drawings.

4 is a graph illustrating an operation of a snubber circuit in a DC / DC converter having a couple inductor and a snubber circuit according to the present invention, and FIG. 5 is a couple inductor and snubber circuit according to the present invention. It is a graph for explaining the operation of the DC / DC converter having a.

Referring to FIG. 4, when the snubber circuit 160 is removed from the DC / DC converter 100 having the couple inductor and the snubber circuit according to the present invention, the switching element of the switching unit 110 ( In S2) it can be seen that the circulating current section is shortened compared to FIG. 2.

That is, when the first, second, seventh, eighth switching elements S1, S2, S7, and S8 are turned on, the DC input power source 750V is connected to the + terminal of the input capacitor C1, and the first and second switching elements S1 and S2. ) Through the primary winding of the transformer unit 120 and the seventh and eighth switching elements (S7, S8) and the input capacitor (C1).

Then, the + current is induced into the secondary winding of the transformer unit 120 to generate an AC voltage, which is converted into a DC voltage through the rectifying unit 130 and the filter unit 140 to charge the battery Vbatt.

Subsequently, when the first and eight switching elements S1 and S8 are turned off, the residual current of the primary winding of the transformer unit 120 is determined by the seventh switching element S7 and the fourth and first rectifying diodes D4 and D1. The second winding is circulated back to the primary winding of the transformer unit 120 through the second switching element S2 and disappears.

At this time, the circulating diode Df of the couple inductor unit 150 is turned on to apply a voltage to the couple inductor L1, and a voltage applied to the couple inductor L1 applies a reverse voltage to the secondary winding of the transformer unit 120. Walk to minimize circulating currents.

Subsequently, when the second and seventh switching elements S2 and S7 are turned off, and the fourth and fifth switching elements S4 and S5 and the third and sixth switching elements S3 and S6 are turned on, the current of the DC input power is increased. It is applied in the reverse direction of the primary winding of the transformer unit 120 through the + terminal, fifth and sixth switching elements S5 and S6 of the input capacitor C2 and then inputs to the third and fourth switching elements S3 and S4. Flow to the-end of the capacitor (C2).

Then, the current is induced in the secondary winding of the transformer unit 120 to generate an AC voltage, which is converted into a DC voltage through the rectifying unit 130 and the filter unit 140 to charge the battery Vbatt.

Subsequently, when the fourth and fifth switching elements S4 and S5 are turned off, the residual current of the primary winding of the transformer 120 may be changed by the third switching element S3, the second and third rectifier diodes D2 and D3. In addition, the sixth switching element S6 is circulated back to the primary winding of the transformer unit 120 and disappears.

Then, the above process is repeated.

Meanwhile, as shown in FIG. 4, the voltage vDf applied to the circulating diode Df is about 1400 V due to the inductance of the couple inductor L1, and accordingly, a high breakdown voltage of the circulating diode Df must be applied. The loss occurs due to the VF (forward drop voltage) of the diode, which limits the application of large capacity. At this time, the voltage applied to the fifth diode D5 of the rectifier 130 is also about 800V.

Thus, the snubber circuit 160 was applied across the couple inductor L1 to absorb and discharge the surge voltage applied to the couple inductor L1.

As a result, as shown in FIG. 5, the voltage vDf applied to the circulating diode Df is reduced to about 800V to 600V than before, and thus, the breakdown voltage may be applied.

In addition, it can be seen that the voltage applied to the fifth diode D5 of the rectifier 130 is reduced by about 200V to about 600V.

As those skilled in the art would realize, the described embodiments may be modified in various ways, all without departing from the spirit or scope of the present invention. It is to be understood, however, that the present invention is not limited to the specific forms referred to in the description, but rather includes all modifications, equivalents, and substitutions within the spirit and scope of the invention as defined by the appended claims. Should be.

11, 110: switching unit 12, 120: transformer unit

13, 130: rectifier 14, 140: filter

150: snubber circuit 160: couple inductor

Claims

Switching unit consisting of a plurality of switching elements to alternately switch the DC input power (Vin) to apply a current, and when the current applied in accordance with the switching operation of the switching unit is applied to the primary winding is induced in the secondary winding is AC power And a rectifier for rectifying the AC power output from the secondary winding side of the transformer part to a DC power source and outputting an output voltage, an inductor Lo, and a capacitor Co to output the rectifier part. In the DC / DC converter consisting of a filter unit for filtering the voltage,

A couple inductor unit connected in parallel between the inductor Lo of the filter unit and the rectifying unit to apply a reverse voltage to the secondary winding of the transformer unit to minimize a circulating current section to minimize conduction loss;

And a snubber circuit connected in parallel between the couple inductor unit and the rectifier unit to absorb and discharge a surge voltage generated from the couple inductor unit.
The method of claim 1,

The couple inductor unit,

A DC / DC converter having a couple inductor and a snubber circuit, characterized in that a circulating diode (Df) is connected in series in a forward direction to a couple inductor (L1) and a rear end of the couple inductor (L1) to apply a voltage.
The method of claim 2,

The snubber circuit,

A capacitor Csn having one end connected between the couple inductor L1 and the circulating diode Df, and the other end connected between the inductor Lo and the rectifier of the filter part;

A resistor Rsn connected between the couple inductor L1 and a capacitor Csn; And

DC / DC having a couple inductor and a snubber circuit, wherein an anode is connected to the capacitor Csn and a diode Dsn is connected between the inductor Lo and the rectifier of the filter unit. Converter.
The method of claim 1,

The switching unit,

A DC / DC converter having a couple inductor and a snubber circuit, which is selected from half bridge, full bridge, three level half bridge, and three level full bridge.