KR101073598B1 - Multi-parallel Zero-Voltage Switching DC-DC converter and control method therefor - Google Patents

Abstract

Disclosed are a multiple parallel zero voltage switch type full bridge DC-DC converter and a control method thereof. The multi-parallel zero voltage switch type full-bridge DC-DC converter according to the present invention is a multi-parallel zero voltage switch type DC-DC converter in which a plurality of full bridge DC-DC converters are connected in parallel, each adjacent pool. The bridge DC-DC converter is characterized in that it comprises a control unit which operates the ground leg of the full-bridge full-bridge DC-DC converter in the forward direction and the forward leg of the full-bridge DC-DC converter in the backward direction.

Parallel zero voltage full bridge, DC-DC converters, ground legs, fastening legs

Description

Multi-parallel Zero-Voltage Switching DC-DC converter and control method therefor}

Embodiment of the present invention relates to a multi-parallel zero voltage switch type full bridge DC-DC converter and a control method thereof, and the loss of conduction in legs added when multiple DC-DC converters are connected in parallel. Multi-parallel zero voltage switch type, which reduces the loss of conduction by canceling the circulating current in the freewheeling section, and allows zero voltage switching over almost any load range in the additional legs for parallel connection. A full bridge DC-DC converter and a control method thereof.

In general, a DC-DC converter is a device that transforms a DC voltage by converting an input DC into AC and then rectifying by stepping up or down with a transformer. A phase-transition zero-voltage switching type full bridge, which is currently a full bridge DC-DC converter. (Zero Voltage Switching Full Bridge: ZVS FB) DC-DC converters are mainly used.

When large DC-DC converters are required, the same DC-DC converters are generally connected in parallel. At this time, when the parallel connection is used, it is possible to obtain good high frequency characteristics by putting a difference in the phase of each converter. In addition to the high frequency characteristics, the range in which efficiency and zero voltage switching are ensured is almost the same as in a single operation.

1 shows a general zero voltage switching type DC-DC converter. Here, it is labeled as the switching element (S _u1, S _d1) is the fast leg (leading) and named as the leg on the right side is the ground leg (lagging leg) on the left side.

Briefly, the switching characteristics of a general zero-voltage switching DC-DC converter are shifted and applied to the gate as shown in FIG. 2 to control the output voltage. It is delayed by DT compared to legs.

In Fig. 2, (1) is called a leading leg transition, and in this transition, the voltage across the switch can be made the opposite rail voltage only by the energy stored in the leakage inductance L _lk , so that if a sufficient current does not flow, zero voltage switching This does not happen. The timing is very tricky because when one switch is turned off and the other switch is turned on, the voltage must be completely changed and the current must be before changing direction.

In Figure 2 (2) are called ground leg transition (lagging leg transition), so the fast leg transition and contribute to the energy is also transition stored in L _f, not only the energy stored in L _lk otherwise be found that it is always possible ZVS have. And in this transition, only the voltage changes, but the current does not change its direction. That is, timing flows very freely because current flows through the anti-parallel diode of the opposite device that needs to be turned on afterwards.

Another feature of the zero-voltage switching DC-DC converter is that in the free-wheeling section indicated by (3) in FIG. 2, current flows but power is not transferred from primary to secondary since the voltage is zero.

On the other hand, many efforts have been made to reduce switching loss and conduction loss in a large-capacity DC-DC converter using an isolation transformer. Switching losses can be reduced by using zero voltage switching without the aid of auxiliary circuits. However, there is a problem that zero voltage switching is not easy to obtain in a wide range.

In addition, circuits using various auxiliary circuits have been devised to reduce the conduction loss, but there is a problem that the total loss cannot be reduced so much due to the increase of the loss caused by the insertion of the auxiliary circuit.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and reduces the conduction loss in the legs added when a plurality of DC-DC converters are connected in parallel, and the conduction by canceling the circulating current in the freewheeling section. In addition to reducing losses, it is also possible to provide a multi-parallel zero voltage switched full-bridge DC-DC converter and its control method capable of zero voltage switching in almost all load ranges in the additional legs for parallel connection. The purpose.

Multi-parallel zero voltage switch type full bridge DC-DC converter according to an embodiment of the present invention for achieving the above object, a multi-parallel zero voltage switch type DC is connected to a plurality of full bridge DC-DC converter in parallel In the direct current converter, for each adjacent full bridge direct current direct current converter, a control unit which operates the ground leg of the forward full bridge direct current direct current converter and the forward leg of the forward full bridge direct current direct current converter in the same manner. Characterized in that it comprises a.

According to another exemplary embodiment of the present invention, a multiple parallel zero voltage switch type full bridge DC-DC converter includes a plurality of first ends connected to a positive terminal of a direct current (DC) input voltage. 1 switch; A plurality of second switches having one end connected to a negative terminal of the DC input voltage; And the other end of each of the first switches and the other end of each of the second switches are connected between the respective contacts connected in a one-to-one manner, and the current and the voltage of the primary side according to the opening and closing operations of the first switch and the second switch are connected to the secondary side. It characterized in that it comprises a plurality of high-frequency transformer to induce to.

Here, the multi-parallel zero voltage switch type full bridge DC-DC converter may further include a controller for controlling on / off of each first switch and each second switch.

In this case, the controller may include each of the first switch and the first switch and the second switch in a one-to-one connection, such that each of the first switch and the rear leg of the leg move forwards a predetermined time with respect to the leg of the forward leg. It is desirable to control each second switch.

In order to achieve the above object, a control method of a multi-parallel zero voltage switch type DC-DC converter according to an embodiment of the present invention includes a plurality of first switches and DC input voltages of which one end is connected to a positive terminal of a DC input voltage. A plurality of second switches, one end of which is connected to the negative terminal, and the other end of each of the first switch and the other end of each of the second switch is connected between the one-to-one contact and the opening and closing operation of the first switch and the second switch In the control method of a multi-parallel zero voltage switch type DC-DC converter having a plurality of high frequency transformers for inducing current and voltage of the primary side to the secondary side, the first switch and the second switch are connected one-to-one. Turning on a first switch within any of the plurality of legs formed; And turning on the first switch in the leg connected to the other end of the high frequency transformer, one end of which is connected to the first switch to be turned on among the plurality of high frequency transformers, at a time delayed by a predetermined time.

Here, in the control method of the multi-parallel zero voltage switch type DC-DC converter, it is preferable to alternately turn on / off the first switch and the second switch in the same leg.

As described above, according to the exemplary embodiment of the present invention, when the plurality of DC-DC converters are connected in parallel, the conduction loss in the legs added is reduced, and the circulating current in the freewheeling period is canceled. In addition to reducing conduction losses, zero voltage switching is possible over almost all load ranges in the additional legs for parallel connection.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In addition, in describing the component of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected or connected to that other component, but between components It will be understood that may be "connected", "coupled" or "connected".

3 is a diagram illustrating a multiple parallel zero voltage switching type full bridge DC-DC converter according to an embodiment of the present invention.

Referring to the drawings, in the multiple parallel zero voltage switching type full bridge DC-DC converter, a plurality of full bridge DC-DC converters are connected in parallel. At this time, the control unit (not shown) is a ground leg of the full bridge DC-DC converter in the forward direction and the full bridge DC-DC in the backward direction as shown by a dotted line for each adjacent full bridge DC-DC converter. Operate the forward legs of the transducer in the same way.

Here, a high frequency transformer as shown in Figs. 4A and 4B is connected between the connection terminals A1 and B1 of each full bridge DC-DC converter and the connection terminals A2 and B2, respectively.

Each full-bridge DC-DC converter is applied to the gate by shifting the phase of the switching signal to control the output voltage of the high frequency transformer, the gate signal of a pair of switches located on the ground leg is located in the forward leg Delay time (DT) is applied to the gate signals of the pair of switches. During this delay, a low impedance path is created through the anti-parallel diode of each switch in the fastening leg, and the energy stored in the primary leakage inductance of the high frequency transformer is circulated through the low impedance path. In addition, the energy stored in the leakage inductance is used to discharge the energy stored in the parasitic capacitor installed in each switch of the ground leg, which causes each switch to perform a zero voltage switching operation.

At this time, if the current flowing into each high frequency transformer is i ₁ and i ₂ , when the ground leg of the full bridge DC-DC converter in the forward direction and the forward leg of the full bridge DC-DC converter in the backward direction are operated in the same manner. The two legs can be combined into one. When switching takes place in a single leg, there is little change in current due to the ground leg transition in a full-bridge full-bridge DC-DC converter. Therefore, the voltage across the switching in the omni-directional full bridge DC-DC converter can be surely changed to the voltage of the opposite rail, and in the backward full bridge DC-DC converter the current changes rapidly because of the forward leg transition, but the composite current flows into the diode. The length of the section is very long, so there is a very large fox in the timing.

At the end of the transition, the forward full-bridge DC-DC converter is in the freewheeling section, and in the powering section, the currents flowing from both transformers to the switch element are reversed and canceled each other. do. This operation reduces the conduction loss. The current waveform by each full bridge DC-DC converter is as shown in FIG.

6 is a diagram illustrating a multiple parallel zero voltage switching type DC-DC converter according to another embodiment of the present invention.

Referring to the drawings, a multi-parallel zero voltage switching type DC-DC converter includes a plurality of first switches Su1, Su2, Su3, ... which have one end connected to a positive terminal of a DC (Direct Current) input voltage. , Sum), a plurality of second switches (Sd1, Sd2, Sd3, ..., Sdm) having one end connected to a negative terminal of the DC input voltage, and each of the first switches (Su1, Su2, Su3, ...). The other end of .., Sum and the other end of each of the second switches Sd1, Sd2, Sd3, ..., Sdm are connected between the contact points connected one-to-one, and the first switch Su1, Su2, Su3 , ..., Sum) and the high frequency transformers T1, T2, T3, which induce current and voltage of the primary side to the secondary side according to the opening and closing operations of the second switches Sd1, Sd2, Sd3, ..., Sdm. ..., Tm-1). Here, each of the high frequency transformers T1, T2, T3, ..., Tm-1 is as shown in FIG. At this time, the load connected to the secondary side of each transformer may be used in series, parallel or independently depending on the situation.

Preferably, the multi-parallel zero voltage switch type DC-DC converter comprises each of the first switches Su1, Su2, Su3, ..., Sum and the second switches Sd1, Sd2, Sd3, ..., The controller 610 further controls on / off of the Sdm.

Here, the first switches Su1, Su2, Su3, ..., Sum and the second switches Sd1, Sd2, Sd3, ..., Sdm are each connected one-to-one to form a plurality of legs. That is, the first switch Su1 and the second switch Sd1 are connected one-to-one to form a leg 1, and the second switch Su2 and the second switch Sd2 are connected to one-to-one to form a leg 2. The same applies to other first switches and second switches.

The control unit 610 is one of a plurality of legs formed by connecting each of the first switch (Su1, Su2, Su3, ..., Sum) and the second switch (Sd1, Sd2, Sd3, ..., Sdm) one to one , The first switches Su1, Su2, Su3, ..., Sum and the respective second switches Sd1, Sd2, Sd3 so that the operation of the legs in the backward direction lags the operation of the legs in the forward direction for a predetermined time. , ..., Sdm) on / off control. That is, as shown in FIG. 8, the leg 2 operates to lag behind the leg 1 by the delay time DT, and the leg 3 operates to lag behind the leg 2 by the delay time DT. The same applies to other legs below.

9 is a flowchart illustrating a control method of a multiple parallel zero voltage switch type DC-DC converter according to an exemplary embodiment of the present invention. 8 and 9 will be described in detail a control method of a multi-parallel zero voltage switch type DC-DC converter according to an embodiment of the present invention.

For a multiple parallel zero voltage switch type DC-DC converter in which a plurality of full bridge DC-DC converters are connected in parallel, the first left leg 1 is operated. That is, the first switch Su1 of the leg 1 is turned on (S901). However, the switch that is turned on preferentially is not limited thereto, and may select any leg and turn on the first switch within the leg. Also, instead of turning on the first switch, the second switch may be turned on first.

When the first switch Su1 in the leftmost leg 1 is turned on, at a time behind the turn-on of the first switch Su1 of the leg 1, a predetermined time DT is located in the leg 2 located in the rear direction adjacent to the leg 1. The first switch Su2 is turned on (S903).

In addition, after the first switch Su2 in the leg 2 is turned on, at a time behind the predetermined time DT after the turn-on of the first switch Su2 in the leg 2, the legs 3 in the leg 3 positioned laterally adjacent to the leg 2 are located. The first switch Su3 is turned on. In this manner, the first switches Su4, Su5, ..., Sum in the adjacent rear legs are sequentially turned on.

On the other hand, the first switch (Su1, Su2, Su3, ..., Sum) and the second switch (Sd1, Sd2, Sd3, ..., Sdm) in each same leg are alternately turned on / off control It is preferable. That is, when the first switch in the same leg is turned on, it is preferable that the second switch is turned off, and when the second switch is turned on, the first switch is preferably turned off.

In addition, as illustrated in FIG. 8, the first switch and the second switch in the same leg may be simultaneously turned on / off. That is, while the first switch Su1 in the leg 1 is turned off, the second switch Sd1 may be turned on at the same time (S905). 8 shows the turn-on of the first switch in the positive direction and the turn-on of the second switch in the negative direction.

Similarly, when the first switch Su2 of the leg 2 adjacent to the leg 1 is turned off, the second switch Sd2 of the leg 2 may be turned on at the same time (S907). In this manner, as in the case of turn-on, the turn-off also proceeds sequentially from the front direction to the rear direction.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. In other words, within the scope of the present invention, all of the components may be selectively operated in combination with one or more. In addition, although all of the components may be implemented in one independent hardware, each or all of the components may be selectively combined to perform some or all functions combined in one or a plurality of hardware. It may be implemented as a computer program having a. Codes and code segments constituting the computer program may be easily inferred by those skilled in the art. Such a computer program may be stored in a computer readable storage medium and read and executed by a computer, thereby implementing embodiments of the present invention. The storage medium of the computer program may include a magnetic recording medium, an optical recording medium, a carrier wave medium, and the like.

In addition, the terms "comprise", "comprise" or "having" described above mean that the corresponding component may be inherent unless specifically stated otherwise, and thus excludes other components. It should be construed that it may further include other components instead. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. Terms used generally, such as terms defined in a dictionary, should be interpreted to coincide with the contextual meaning of the related art, and shall not be interpreted in an ideal or excessively formal sense unless explicitly defined in the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 shows a general zero voltage switching type DC-DC converter.

FIG. 2 is a diagram illustrating an operating waveform of the zero voltage switch type DC-DC converter of FIG. 1.

3 is a diagram illustrating a multiple parallel zero voltage switch type full bridge DC-DC converter according to an embodiment of the present invention.

4 is a diagram illustrating an example of a high frequency transformer used in the multiple parallel zero voltage switch type full bridge DC-DC converter of FIG. 3.

FIG. 5 is a diagram illustrating a current waveform by the multiple parallel zero voltage switch type full bridge DC-DC converter of FIG. 3.

6 is a diagram illustrating an example of a multiple parallel zero voltage switch type full bridge DC-DC converter according to another embodiment of the present invention.

7 is a diagram illustrating an example of a high frequency transformer used in the multiple parallel zero voltage switch type full bridge DC-DC converter of FIG. 6.

FIG. 8 is a diagram illustrating waveforms of each leg of FIG. 6.

9 is a flowchart illustrating a control method of a multiple parallel zero voltage switch type full bridge DC-DC converter according to an exemplary embodiment of the present invention.

Claims (6)

In a multiple parallel zero voltage switch type DC-DC converter in which a plurality of full bridge DC-DC converters are connected in parallel, A plurality of high frequency transformers connected between an advance leg and a ground leg of each said full bridge DC-DC converter; And For each adjacent full bridge DC-DC converter, the ground leg of the full bridge DC-DC converter in the forward direction and the forward leg of the full bridge DC-DC converter in the backward direction are operated equally, The ground leg of the full bridge DC-DC converter operates to have a delay time set for the forward leg of the full bridge DC-DC converter in all directions, and the high frequency transformer of the full bridge DC-DC converter in all directions after the transition. A control unit for canceling the current flowing from the high frequency transformer of the full bridge DC-DC converter in the rear direction to the switching element Multiple parallel type zero-voltage switch type DC-DC converter comprising a. A plurality of first switches having one end connected to a positive terminal of a direct current (DC) input voltage; A plurality of second switches having one end connected to a negative terminal of the DC input voltage; The other end of each of the first switches and the other end of each of the second switches are connected between respective contacts connected in a one-to-one manner, and the current and voltage of the primary side according to the opening and closing operations of the first switch and the second switch. A plurality of high frequency transformer for inducing the secondary side; And A control unit for controlling on / off for each of the first switch and each of the second switch Including, but the control unit, For each adjacent full bridge DC-DC converter, the ground leg of the full bridge DC-DC converter in the forward direction and the forward leg of the full bridge DC-DC converter in the backward direction are operated equally, but the pull in the forward direction is applied. The ground leg of the bridge DC-DC converter operates to have a delay time set for the forward leg of the full bridge DC-DC converter in all directions, and corresponds from the high frequency transformer of the full bridge DC-DC converter in all directions after the transition. Controlling to cancel the current flowing through the first switch and the second switch and the current flowing through the corresponding first switch and the second switch from the high frequency transformer of the full bridge DC-DC converter in a backward direction. Multiple parallel zero voltage switch type DC-DC converters. delete delete A plurality of first switches connected at one end to a positive terminal of the DC input voltage, a plurality of second switches connected at one end to a negative terminal of the DC input voltage, and a second end of each of the first switches and each of the second switches Multiple parallel type zeros having a plurality of high frequency transformers connected to each other connected in one-to-one contact and inducing current and voltage of the primary side to the secondary side according to the opening and closing operations of the first switch and the second switch. In the control method of the voltage-switched DC-DC converter, Turning on a first switch in an arbitrary leg of a plurality of legs formed by connecting the first switch and the second switch one-to-one; And The first switch in the leg connected to the other end of the high frequency transformer, one end of which is connected to the first switch to be turned on of the plurality of high frequency transformer is turned on at a time behind a predetermined time, and for each adjacent full bridge DC-DC converter The ground leg of the full bridge DC-DC converter in the direction and the forward leg of the full bridge DC-DC converter in the backward direction are operated equally, and corresponding to the high-frequency transformer of the full bridge DC-DC converter in the forward direction after the transition. Controlling the current flowing through the first switch and the second switch and the current flowing through the corresponding first switch and the second switch from the high frequency transformer of the full bridge DC-DC converter in a backward direction to be canceled out; Control method of a multi-parallel zero voltage switch type DC-DC converter comprising a. The method of claim 5, A control method of a multiple parallel zero voltage switch type DC-DC converter, characterized in that alternately on / off control of the first switch and the second switch in the same leg.

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