TW201947862A - Simplified unidirectional isolated multi-level DC-DC converter and method thereof - Google Patents

Abstract

A multi-level DC-DC converter device includes an inverter, a 3-winding high-frequency transformer, a first full-wave rectifier, a second full-wave rectifier, a selective circuit and a filter circuit. A first winding at a primary side of the high-frequency transformer connects with the inverter while a second winding and a third winding at a secondary side of the high-frequency transformer connect with the first full-wave rectifier and the second full-wave rectifier, respectively. The selective circuit connects with DC output ports of the first full-wave rectifier and the second full-wave rectifier, thereby operationally selecting two serially-connected full-wave rectifiers or single full-wave rectifier to output two voltage levels performed as a multi-level output voltage. The filter circuit connects between the selective circuit and a load for filtering harmonics and outputting a DC voltage.

Description

   Simplified unidirectional isolated multi-stage DC-DC power conversion device and method   

The invention relates to a simplified unidirectional isolated multi-level DC-DC power conversion device and a method thereof; in particular, it relates to a simplified unidirectional isolated multi-level DC-DC power conversion device and a method thereof capable of reducing the volume; More particularly, it relates to a simplified unidirectional isolated multi-stage DC-DC power conversion device and method capable of reducing output voltage and current ripple.

Generally speaking, the conventional isolated DC-DC power converter has been widely used in various technical fields. Although the traditional isolated DC-DC power converter has the advantages of simple control, it has the disadvantages of low efficiency, high ripple, high electromagnetic interference, and large capacity of the filter circuit to be used. In contrast, although the conventional multi-order DC-DC power converter has the disadvantage of more complex control, it has the advantages of relatively high efficiency, relatively small electromagnetic interference, and a small capacity of the filter circuit to be used. .

For example, FIG. 1 shows a schematic diagram of a conventional multi-stage DC-DC power conversion device, which mainly includes four blocks. Please refer to FIG. 1, the conventional multi-stage DC-DC power conversion device 1 includes a double half-bridge inverter 11, a double high-frequency transformer 12, a full-bridge rectifier 13 and an output filter circuit 14. The multi-stage DC-DC power conversion device 1 is composed. In addition, the double half-bridge inverter 11 needs to use four power switches and four capacitors.

Please refer to FIG. 1 again, the double half-bridge inverter 11 is composed of two half-bridge inverters connected in series, and the double high-frequency transformer 12 includes two high-frequency transformers connected to the double half-bridge, respectively. AC terminals of two half-bridge inverters of the inverter 11. In the power conversion operation, by controlling the power switch switching mode of the double half-bridge inverter 11, the primary side of the dual high-frequency transformer 12 generates three kinds of voltages. In addition, after the secondary side of the dual high-frequency transformer 12 is properly rectified by the full-bridge rectifier 13, two voltage levels can be output.

However, in practical applications, since the double half-bridge inverter 11 includes two half-bridge inverters, the control thereof is complicated, and four capacitors need to be used. In addition, since the capacitance values of the four capacitors may be different, the voltages of the capacitors may be inconsistent, and the control thereof may be more complicated. In addition, the dual high-frequency transformer 12 includes two high-frequency transformers, which must use two iron cores, which results in increased cost and bulk.

For example, another conventional multi-level DC-DC power converter, such as the invention patent of "Unidirectional Isolated Multi-level DC-DC Power Conversion Device and Method" of the Republic of China Patent Publication No. TW-I575861, corresponds to the United States Invention Patent Publication No. US-20170207712, "Unidirectional isolated multi-level DC-DC converter and method thereof" application, discloses a unidirectional isolated multi-stage DC-DC power conversion device and method thereof.

FIG. 2 is a schematic diagram showing the architecture of a conventional unidirectional isolated multi-stage DC-DC power conversion device of the Republic of China Patent Bulletin No. TW-I575861 and the US Patent Application No. US-20170207712. Please refer to FIG. 2, the conventional unidirectional isolated multi-stage DC-DC power conversion device 2 includes an inverter 21, a high-frequency transformer 22 with three windings, a first full-bridge rectifier 23, and a first Two full-bridge rectifiers 24, a selection circuit 25 and a filter circuit 27, and the selection circuit 25 has a first input terminal, a second input terminal and an output terminal.

Please refer to FIG. 2 again, the input terminal of the inverter 21 is connected in parallel with an input DC voltage source 28, and the inverter 21 is selected from a half-bridge inverter and a full-bridge inverter. [Full-bridge] inverter or other structure inverter.

Please refer to FIG. 2 again, the half-bridge inverter includes two power electronic switches and two capacitors, and the two power electronic switches and two capacitors are properly connected. In addition, the full-bridge inverter includes four power electronic switches and a capacitor, and the four power electronic switches and a capacitor are properly connected.

Please refer to FIG. 2 again, the first full-bridge rectifier 23 has a first DC positive output terminal and a first DC negative output terminal, and the first DC positive output terminal and the first DC The negative output terminal is connected in parallel with a first capacitor 261 to form a first output DC voltage. In contrast, the second full-bridge rectifier 24 has a second DC positive output terminal and a second DC negative output terminal, and the second DC positive output terminal and the second DC negative output terminal are connected in parallel to a second capacitor 262 A second output DC voltage is formed.

Please refer to FIG. 2 again, the unidirectional isolated multi-stage DC-DC power conversion device outputs two voltage levels to form a multi-stage output voltage, and outputs a DC voltage at an output terminal 29 through the filter circuit 27 Vout.

FIG. 3 shows a schematic diagram of the structure of another conventional unidirectional isolated multi-stage DC-DC power conversion device of the Republic of China Patent Publication No. TW-I575861 and US Patent Application Publication No. 20170207712, which corresponds to the second The figure uses a unidirectional isolated multi-stage DC-DC power conversion device. Please refer to FIG. 3. In contrast, the inverter 21 includes an upper power electronic switch S1, a lower power electronic switch S2, and two capacitors C1 and C2.

Please refer to Figures 2 and 3, in fact, the first full-bridge rectifier 23, a second full-bridge rectifier 24, and the selection circuit 25 of the unidirectional isolated multi-stage DC-DC power conversion device 2 need to be used. At least 9 diodes D1, D2, D3, D4, D5, D6, D7, D8, D9, so it has relatively complicated technical structure, increased manufacturing cost and increased product volume.

Obviously, the conventional multi-stage DC-DC power converter still needs to improve its structural or component technical disadvantages in architecture. Therefore, the conventional DC-DC power converter or isolated multi-stage DC-DC power converter necessarily has a need to further provide or develop a simplified isolated multi-stage DC-DC power converter. The foregoing technical description is only a reference for the technical background of the present invention and describes the current state of technological development, and it is not intended to limit the scope of the present invention.

In view of this, in order to meet the above requirements, the present invention provides a simplified unidirectional isolated multi-stage DC-DC power conversion device and a method thereof, which include an inverter, a high-frequency transformer with three windings, and a first A full-wave rectifier, a second full-wave rectifier, a selection circuit and a filter circuit, which use only a single inverter and a single high-frequency transformer with three windings, and control the selection circuit to generate a The pulse voltage of low harmonic voltage is output to the filter circuit to reduce the capacity of the filter circuit. The first full-wave rectifier includes only two first diodes, and the second full-wave rectifier includes only two first diodes. Two diodes to simplify the overall structure, reduce manufacturing costs and reduce product volume, in order to improve the technical shortcomings of conventional unidirectional isolated multi-stage DC-DC power conversion devices.

The main object of the preferred embodiment of the present invention is to provide a simplified unidirectional isolated multi-stage DC-DC power conversion device and method thereof, which include an inverter, a high-frequency transformer with three windings, and a first full-wave A rectifier, a second full-wave rectifier, a selection circuit and a filter circuit, which use only a single inverter and a single high-frequency transformer with three windings, and a low harmonic can be generated by controlling the selection circuit The pulse voltage of the wave voltage is output to the filter circuit to reduce the capacity of the filter circuit. The first full-wave rectifier includes only two first diodes, and the second full-wave rectifier includes only two second two. Polar body to achieve the purpose of simplifying the overall structure, reducing product volume, reducing manufacturing costs and improving operating efficiency.

In order to achieve the above object, the unidirectional isolated multi-stage DC-DC power conversion device of the preferred embodiment of the present invention includes: an inverter for connecting to an input voltage source and generating a fixed pulse width high High-frequency AC voltage, and the inverter includes an AC output terminal; a high-frequency transformer with three windings, which includes a primary side and a secondary side, a primary side of the high-frequency transformer has a first winding, and The first winding of the primary side of the high-frequency transformer is connected to the AC output of the inverter, and the secondary side of the high-frequency transformer with three windings has a second winding and a third winding; a first full-wave rectifier Its input is connected to the second winding on the secondary side of the high-frequency transformer, and the first full-wave rectifier has a first DC positive output terminal and a first DC negative output terminal, and the first DC The positive output terminal and the first DC negative output terminal are connected in parallel with a first capacitor to form a first output DC voltage; a second full-wave rectifier whose input is connected to a third winding on the secondary side of the high-frequency transformer, And the second full-wave rectification The device has a second DC positive output terminal and a second DC negative output terminal. The second DC positive output terminal and the second DC negative output terminal are connected in parallel to a second capacitor to form a second output DC voltage. The second DC positive output terminal of the two full-wave rectifiers is connected to the first DC negative output terminal of the first full-wave rectifier; a selection circuit having a first input terminal, a second input terminal and an output terminal, The first input terminal is connected to the first DC positive output terminal of the first full-wave rectifier, and the second input terminal is connected to the first DC negative output terminal of the first full-wave rectifier and the second full-wave rectifier. A second DC positive output terminal of the wave rectifier; and a filter circuit connected to the output terminal of the selection circuit and the second DC negative output terminal of the second full wave rectifier.

The inverter of the preferred embodiment of the present invention is selected from a half-bridge inverter or a full-bridge inverter.

In the preferred embodiment of the present invention, the selection circuit is operated to control the output voltage of the selection circuit to be the sum of the first output DC voltage and the second output DC voltage, or to be a single second output DC voltage and a voltage drop. The voltages are subtracted in order to output two voltage levels to form a multi-stage output voltage, and a DC voltage is output through the filter circuit.

The voltage drop voltage of the preferred embodiment of the present invention is a voltage drop voltage of a diode.

The selection circuit of the preferred embodiment of the present invention includes a power electronic switch and a diode, and the power electronic switch is connected between a first input terminal of the selection circuit and an output terminal of the selection circuit.

In the preferred embodiment of the present invention, the anode of the diode is connected to the second input terminal of the selection circuit, and the cathode of the diode is connected to the output terminal of the selection circuit.

In a preferred embodiment of the present invention, the power electronic switch of the selection circuit is controlled by operation, so that the output voltage of the selection circuit can be the sum of the first output DC voltage and the second output DC voltage or only the second output DC voltage. Subtract from the voltage drop voltage so as to output two voltage levels to form a multi-stage output voltage, and output a DC voltage through the filter circuit.

The filter circuit according to a preferred embodiment of the present invention includes an inductor and a capacitor.

In order to achieve the above object, a simplified unidirectional isolated multi-stage DC-DC power conversion method according to a preferred embodiment of the present invention includes: providing an inverter, a high-frequency transformer with three windings, a first full-wave rectifier, and a A second full-wave rectifier, a selection circuit and a filter circuit, and the selection circuit has a first input terminal, a second input terminal and an output terminal; the inverter is connected to an input DC voltage source and generates A high-frequency AC voltage with a fixed pulse width; the primary side of the high-frequency transformer with three windings has a first winding, and the first winding of the primary side of the high-frequency transformer with three windings is connected to the inverter An AC output, and the secondary side of the high frequency transformer with three windings has a second winding and a third winding; the input of the first full wave rectifier is connected to the high frequency transformer with three windings A secondary winding on the secondary side, and the first full-wave rectifier has a first DC positive output terminal and a first DC negative output terminal, and the first DC positive output terminal and the first DC negative output Connected in parallel The capacitor forms a first output DC voltage; the input of the second full-wave rectifier is connected to the third winding on the secondary side of the high-frequency transformer with three windings, and the second full-wave rectifier has a second DC A positive output terminal and a second DC negative output terminal, and the second DC positive output terminal and the second DC negative output terminal are connected in parallel with a second capacitor to form a second output DC voltage, and the second full-wave rectifier The second DC positive output terminal is connected to the first DC negative output terminal of the first full-wave rectifier; the first input terminal of the selection circuit is connected to the first DC positive output terminal of the first full-wave rectifier, and Connecting a second input terminal of the selection circuit to a first DC negative output terminal of the first full-wave rectifier and a second DC positive output terminal of the second full-wave rectifier; and connecting the filter circuit to the selection circuit An output terminal of the second full-wave rectifier and a second direct-current negative output terminal of the second full-wave rectifier; wherein the selection circuit is controlled by operation so that the output voltage of the selection circuit is equal to the first output DC voltage and the second output DC voltage Or a single DC voltage output of the second subtracting a voltage drop, so as to output two kinds of voltage levels to form a multi-level output voltage, and output via the filter circuit is a DC voltage.

The voltage drop voltage of the preferred embodiment of the present invention is a voltage drop voltage of a diode.

The inverter of the preferred embodiment of the present invention is selected from a half-bridge inverter or a full-bridge inverter.

The selection circuit of the preferred embodiment of the present invention includes a power electronic switch and a diode, and the power electronic switch is connected between a first input terminal of the selection circuit and an output terminal of the selection circuit.

In the preferred embodiment of the present invention, the anode of the diode is connected to the second input terminal of the selection circuit, and the cathode of the diode is connected to the output terminal of the selection circuit.

In a preferred embodiment of the present invention, the power electronic switch of the selection circuit is controlled by operation, so that the output voltage of the selection circuit can be the sum of the first output DC voltage and the second output DC voltage or only the second output DC voltage. Subtract from the voltage drop voltage so as to output two voltage levels to form a multi-stage output voltage, and output a DC voltage through the filter circuit.

The filter circuit according to a preferred embodiment of the present invention includes an inductor and a capacitor.

1‧‧‧Multi-level DC-DC Power Conversion Device

11‧‧‧Double Half-Bridge Inverter

12‧‧‧Double high frequency transformer

13‧‧‧Full Bridge Rectifier

14‧‧‧ output filter circuit

2‧‧‧ one-way isolated multi-stage DC-DC power conversion device

21‧‧‧ Inverter

S ₁ ‧‧‧ on power electronic switch

S ₂ ‧‧‧ Power electronic switch

C ₁ ‧‧‧Capacitor

C ₂ ‧‧‧Capacitance

22‧‧‧High frequency transformer with three windings

23‧‧‧First Full Bridge Rectifier

24‧‧‧Second Full Bridge Rectifier

D ₁ ‧‧‧ Diode

D ₂ ‧‧‧ Diode

D ₃ ‧‧‧ Diode

D ₄ ‧‧‧ Diode

D ₅ ‧‧‧ Diode

D ₆ ‧‧‧ Diode

D ₇ ‧‧‧ Diode

D ₈ ‧‧‧ Diode

D ₉ ‧‧‧ Diode

25‧‧‧Selection circuit

261‧‧‧First capacitor

262‧‧‧Second capacitor

27‧‧‧Filter circuit

28‧‧‧Input DC voltage source

29‧‧‧ output

V _in ‧‧‧ input voltage

V _out ‧‧‧DC voltage

3‧‧‧ Simplified unidirectional isolated multi-stage DC-DC power conversion device

31‧‧‧ Inverter

32‧‧‧High frequency transformer with three windings

321‧‧‧first winding

322‧‧‧second winding

323‧‧‧Third Winding

331‧‧‧The first full wave rectifier

332‧‧‧Second Full Wave Rectifier

341‧‧‧First capacitor

342‧‧‧Second capacitor

35‧‧‧Selection circuit

351‧‧‧Power Electronic Switch

352‧‧‧diode

36‧‧‧Filter circuit

361‧‧‧Inductance

362‧‧‧Capacitor

37‧‧‧Input DC voltage source

38‧‧‧output

S1, S2, S3, S4, S5, S6, S7, S8‧‧‧ steps

Figure 1: Schematic diagram of a conventional multi-stage DC-DC power conversion device.

Figure 2: Schematic diagram of another conventional unidirectional isolated multi-stage DC-DC power conversion device.

Figure 3: Schematic diagram of another conventional unidirectional isolated multi-stage DC-DC power conversion device.

Figure 4: Schematic diagram of a simplified unidirectional isolated multi-stage DC-DC power conversion device according to a preferred embodiment of the present invention.

Figure 5 (A): A schematic diagram of a simplified unidirectional isolated multi-stage DC-DC power conversion device using a half-bridge inverter in a preferred embodiment of the present invention.

Figure 5 (B): A schematic diagram of a simplified unidirectional isolated multi-stage DC-DC power conversion device using a full-bridge inverter in a preferred embodiment of the present invention.

FIG. 6 is a schematic flowchart of a simplified unidirectional isolated multi-stage DC-DC power conversion method according to a preferred embodiment of the present invention.

In order to fully understand the present invention, the preferred embodiments will be described in detail below with reference to the accompanying drawings, which are not intended to limit the present invention.

The simplified unidirectional isolated multi-stage DC-DC power conversion device of the preferred embodiment of the present invention, its operation and control method are applicable to various multi-stage power conversion devices or similar functional devices, but it is not intended to limit the scope of the present invention .

FIG. 4 illustrates a schematic diagram of a simplified unidirectional isolated multi-stage DC-DC power conversion device according to a preferred embodiment of the present invention. Please refer to FIG. 4. The simplified unidirectional isolated multi-stage DC-DC power conversion device 3 of the preferred embodiment of the present invention includes an inverter 31, a high-frequency transformer 32 with three windings, and a first The wave rectifier 331, a second full-wave rectifier 332, a selection circuit 35 and a filter circuit 36, and the selection circuit 35 has a first input terminal, a second input terminal and an output terminal.

Please refer to FIG. 4 again. For example, the input terminal of the inverter 31 is connected in parallel with an input DC voltage source 37, and the inverter 31 may be selected from a half-bridge inverter and a full-bridge inverter. Inverter or other structure inverter. An input terminal of the inverter 31 (the left side of the component) is connected in parallel with an input DC voltage source 37. In addition, the inverter 31 (the right side of the element) includes an AC output terminal.

Fig. 5 (A) illustrates a schematic diagram of a simplified unidirectional isolated multi-stage DC-DC power conversion device of the preferred embodiment of the present invention using a half-bridge inverter. Please refer to FIG. 5 (A). For example, the half-bridge inverter includes an upper power electronic switch S1, a lower power electronic switch S2, and two capacitors C1, C2, and the upper power electronic switch S1, The lower power electronic switch S2 and the two capacitors C1 and C2 are properly electrically connected.

FIG. 5 (B) illustrates a simplified schematic diagram of a preferred unidirectional isolated multi-stage DC-DC power conversion device according to the present invention, which can use a full-bridge inverter. Please refer to FIG. 5 (B). For example, the full-bridge inverter includes four power electronic switches S1, S2, S3, S4 and a capacitor C1, and the four power electronic switches S1, S2, S3 , S4 and capacitor C1 are properly electrically connected.

Please refer to FIG. 4 again. For example, the high-frequency transformer 32 with three windings includes a primary side and a secondary side, and the primary side has a first winding 321, and the secondary side has a second The winding 322 and a third winding 323. The turns ratio of the first winding 321, the second winding 322, and the third winding 323 is n1: n2: n3, and the second winding 322 and the third winding 323 are center-tapped windings. The first winding 321 of the three-winding high-frequency transformer 32 is appropriately connected to the AC output terminal of the inverter 31.

Please refer to FIG. 4 again. For example, the first full-wave rectifier 331 includes two diodes D1, D2, and the two diodes D1, D2, and the second winding 322 form the first Full-wave rectifier 331 to simplify the overall structure. The AC input of the first full-wave rectifier 331 is connected to the second winding 322 of the three-winding high-frequency transformer 32, and the first full-wave rectifier 331 has a first DC positive output terminal and a first Current negative output terminal, and the first DC positive output terminal and the first DC negative output terminal are connected in parallel to a first capacitor 341 to form a first output DC voltage.

Please refer to FIG. 4 again. For example, the second full-wave rectifier 332 includes two diodes D3 and D4, and the two diodes D3 and D4 and the third winding 323 form the second diode. Full-wave rectifier 332 to simplify the overall structure. The input of the second full-wave rectifier 332 is connected to the third winding 323 of the three-winding high-frequency transformer 32, and the second full-wave rectifier 332 has a second DC positive output terminal and a second DC negative output Terminal, and the second DC positive output terminal and the second DC negative output terminal are connected in parallel with a second capacitor 342 to form a second output DC voltage, and the second DC positive output terminal of the second full-wave rectifier 332 is connected to A first DC negative output terminal of the first full-wave rectifier 331.

Please refer to FIG. 4 again. For example, the selection circuit 35 includes a power electronic switch 351 and a diode 352. The first positive DC output terminal of the power electronic switch 351 connected to the first full-wave rectifier 331 is formed as the first input terminal of the selection circuit 35, and the anode of the diode 352 is connected to the first full-wave rectifier. The first DC negative output terminal of the rectifier 331 and the second DC positive output terminal of the second full-wave rectifier 332 are formed as the second input terminal of the selection circuit 35, and the cathode of the diode 352 is connected to the The other end of the power electronic switch 351 is formed as an output terminal of the selection circuit 35.

Please refer to FIG. 4 again. For example, the filter circuit 36 includes an inductor 361 and a capacitor 362. The filter circuit 36 is connected in parallel to the output terminal of the selection circuit 35 and the second DC negative output terminal of the second full-wave rectifier 332.

Please refer to FIG. 4 again. For example, the power electronic switch 351 of the selection circuit 35 is controlled by operation, so that the output voltage of the selection circuit 35 can be the first output DC voltage and the second output DC voltage. And or just subtract the second output DC voltage from the voltage drop voltage (or other voltage drop voltage) of the diode 352, so as to output two voltage levels to form a multi-stage output voltage, and pass through the filter circuit 36 outputs a DC voltage Vout at an output terminal 38.

Please refer to Figs. 4 and 5 (A), the power electronic switch S1 and the lower power electronic switch S2 above the inverter 31 are all switched with a fixed duty cycle of 0.5. Therefore, the inverter 31 will output a high-frequency square-wave voltage of a fixed width, and connect the high-frequency square-wave voltage of the fixed width to the first winding 321 of the three-winding high-frequency transformer 32. The second winding 322 and the third winding 323 of the three-winding high-frequency transformer 32 induce high-frequency square wave voltages of the same waveform, and generate the first output through the first full-wave rectifier 331 and the second full-wave rectifier 332, respectively. A DC voltage and the second output DC voltage. Assuming the input voltage is Vin, the turns ratio n2: n3 of the second winding 322 and the third winding 323 of the high-frequency transformer 32 with three windings is 1: 3, then the first output DC voltage is 50V, and the second The output DC voltage is 150V, and the output through the filter circuit 36 is 180V. The first output DC voltage may be less than or equal to the subtraction between the second output DC voltage and the voltage drop voltage of the diode 352. For example, the switching frequency of the switching signal of the power electronic switch 351 is selected to be any multiple of the frequency of the high-frequency square wave voltage of the inverter 31.

Please refer to FIG. 4 again, because when the power electronic switch 351 is turned on, the first output DC voltage and the second output DC voltage form a series supply power, the output voltage of the selection circuit 35 is the first output The sum of the DC voltage and the second output DC voltage (Vin * n2 / n1 + Vin * n3 / n1). Conversely, when the power electronic switch 351 is turned off, the second output DC voltage will be supplied with power via the diode 352, so the output voltage of the selection circuit 35 is the second DC current voltage (Vin * n3 / n1). The selection circuit 35 outputs the output voltages of two voltage levels (Vin * n2 / n1 + Vin * n3 / n1) and (Vin * n3 / n1) to the filter circuit 36. Finally, the output voltage of the selection circuit 35 generates a DC voltage to a load via the filter circuit 36 through an output terminal 38. Among the two voltage levels output by the selection circuit 35 (Vin * n2 / n1 + Vin * n3 / n1 ) Must be higher than the DC voltage of the supplied load, and (Vin * n3 / n1) must be lower (ie, not higher than) the DC voltage of the supplied load.

FIG. 6 illustrates a schematic flow chart of a simplified unidirectional isolated multi-stage DC-DC power conversion method according to a preferred embodiment of the present invention. Please refer to FIG. 4 and FIG. 6. The simplified unidirectional isolated multi-stage DC-DC power conversion method according to the preferred embodiment of the present invention includes step S1. First, an inverter 31 and a high-frequency transformer with three windings are provided. 32. A first full-wave rectifier 331, a second full-wave rectifier 332, a selection circuit 35, and a filter circuit 36, and the selection circuit 35 has a first input terminal, a second input terminal, and an output terminal.

Please refer to FIG. 4 and FIG. 6 again. The simplified unidirectional isolated multi-stage DC-DC power conversion method according to the preferred embodiment of the present invention further includes step S2. Next, the inverter 31 is connected to the input DC voltage. The source 37 generates a high-frequency AC voltage with a fixed pulse width.

Please refer to FIG. 4 and FIG. 6 again. The simplified unidirectional isolated multi-stage DC-DC power conversion method of the preferred embodiment of the present invention further includes step S3. Next, the primary side of the high-frequency transformer 32 with three windings With the first winding 321, the first winding 321 on the primary side of the high-frequency transformer 32 with three windings is connected to an AC output terminal of the inverter 31, and the two of the high-frequency transformer 32 with three windings The secondary side includes the second winding 322 and the third winding 323.

Please refer to FIG. 4 and FIG. 6 again. The simplified unidirectional isolated multi-stage DC-DC power conversion method according to the preferred embodiment of the present invention further includes step S4. Then, the input of the first full-wave rectifier 331 is connected to The second winding 322 on the secondary side of the three-winding high-frequency transformer 32, and the first full-wave rectifier 331 has a first DC positive output terminal and a first DC negative output terminal, and the first The first positive DC output terminal and the first negative DC output terminal are connected in parallel to the first capacitor 341 to form a first output DC voltage.

Please refer to FIG. 4 and FIG. 6 again. The simplified unidirectional isolated multi-stage DC-DC power conversion method according to the preferred embodiment of the present invention further includes step S5. Next, the input of the second full-wave rectifier 332 is connected to The third winding 323 on the secondary side of the three-winding high-frequency transformer 32, and the second full-wave rectifier 332 has a second DC positive output terminal and a second DC negative output terminal, and the second DC positive output terminal The output terminal and the second DC negative output terminal are connected in parallel to the second capacitor 342 to form a second output DC voltage, and the second DC positive output terminal of the second full-wave rectifier 332 is connected to the first full-wave rectifier 331. The first DC negative output terminal.

Please refer to FIG. 4 and FIG. 6 again. The simplified unidirectional isolated multi-stage DC-DC power conversion method according to the preferred embodiment of the present invention further includes step S6. Next, the first input terminal of the selection circuit 35 is connected to A first DC positive output terminal of the first full-wave rectifier 331, and a second input terminal of the selection circuit 35 is connected to the first DC negative output terminal of the first full-wave rectifier 331 and the second full-wave rectifier The second DC positive output terminal of the rectifier 332.

Please refer to FIG. 4 and FIG. 6 again. The simplified unidirectional isolated multi-stage DC-DC power conversion method according to the preferred embodiment of the present invention further includes step S7. Next, the filter circuit 36 is connected to the selection circuit 35. An output terminal and a second DC negative output terminal of the second full-wave rectifier 332.

Please refer to FIG. 4 and FIG. 6 again. The simplified unidirectional isolated multi-stage DC-DC power conversion method according to the preferred embodiment of the present invention further includes step S8. Then, the selection circuit 35 is controlled by operation to make the selection circuit The output voltage of 35 is the sum of the first output DC voltage and the second output DC voltage, or a single subtraction of the second output DC voltage and a voltage drop voltage in order to output two voltage levels to form a multi Step output voltage, and output a DC voltage through the filter circuit 36.

Please refer to FIGS. 3 and 4 again. Traditionally, the first full-bridge rectifier 23, a second full-bridge rectifier 24, and the selection circuit 25 of the unidirectional isolated multi-stage DC-DC power conversion device 2 are required. Use at least 9 diodes D1, D2, D3, D4, D5, D6, D7, D8, D9, as shown in Figure 3; simplified unidirectional isolated multi-stage DC-DC power of the preferred embodiment of the present invention The first full-wave rectifier 331, the second full-wave rectifier 332, and the selection circuit 35 of the conversion device 3 need to use at least five diodes D1, D2, D3, D4, and D5, as shown in FIG. 4, so they have relatively The effect of simplifying the overall structure, reducing manufacturing costs and reducing product volume.

In addition, the voltage of the filter circuit of the conventional isolated DC-DC power conversion device is zero and two voltage levels higher than the DC voltage of the load. Because of the simplified unidirectional isolated multi-level DC-DC power of the preferred embodiment of the present invention, The voltage supplied to the filter circuit 36 in the energy conversion device 3 has smaller voltage harmonics than the voltage supplied to the filter circuit by the conventional isolated DC-DC power conversion device. Therefore, the simplified unidirectional isolated type of the preferred embodiment of the present invention The multi-stage DC-DC power conversion device 3 can reduce the capacity of the filter circuit 36 to achieve the purpose of reducing the overall volume, reducing the manufacturing cost and operating efficiency.

The foregoing preferred embodiment merely exemplifies the present invention and its technical features, and the technology of this embodiment can still be appropriately implemented with various substantially equivalent modifications and / or replacements; therefore, the scope of rights of the present invention shall be subject to the attached patent application The scope defined by the scope shall prevail. The copyright in this case restricts the use to the patent application of the Republic of China.

Claims (15)

    A unidirectional isolated multi-stage DC-DC power conversion device includes: an inverter for connecting to an input voltage source and generating a high-frequency AC voltage with a fixed pulse width; and the inverter Containing an AC output terminal; a three-winding high-frequency transformer including a primary side and a secondary side, a primary side of the high-frequency transformer has a first winding, and a first winding of a primary side of the high-frequency transformer Connected to the AC output of the inverter, and the secondary side of the three-winding high-frequency transformer has a second winding and a third winding; a first full-wave rectifier whose input is connected to the high-frequency transformer Secondary winding on the secondary side, and the first full-wave rectifier has a first DC positive output terminal and a first DC negative output terminal, and the first DC positive output terminal and the first DC negative terminal The output end is connected in parallel with a first capacitor to form a first output DC voltage; a second full-wave rectifier whose input is connected to the third winding on the secondary side of the high-frequency transformer, and the second full-wave rectifier has a The second DC positive output terminal and a A second DC negative output terminal, and the second DC positive output terminal and the second DC negative output terminal are connected in parallel with a second capacitor to form a second output DC voltage, and the second DC positive output of the second full-wave rectifier Terminal is connected to the first DC negative output terminal of the first full-wave rectifier; a selection circuit having a first input terminal, a second input terminal and an output terminal, and the first input terminal is connected to the first A first DC positive output terminal of a full-wave rectifier, and the second input terminal is connected to a first DC negative output terminal of the first full-wave rectifier and a second DC positive output terminal of the second full-wave rectifier; And a filter circuit, which is connected to the output terminal of the selection circuit and the second DC negative output terminal of the second full-wave rectifier.         The unidirectional isolated multi-stage DC-DC power conversion device according to item 1 of the scope of the patent application, wherein the inverter is selected from a half-bridge inverter or a full-bridge inverter.         The unidirectional isolated multi-stage DC-DC power conversion device according to item 1 of the scope of patent application, wherein the output voltage of the selection circuit is controlled to be the first output DC voltage and the second output DC by operating the selection circuit. The sum of the voltages or the single output voltage of the second output DC voltage is subtracted from a voltage drop voltage, so as to output two voltage levels to form a multi-stage output voltage, and output the DC voltage through the filter circuit.         The unidirectional isolated multi-stage DC-DC power conversion device according to item 3 of the scope of patent application, wherein the voltage drop voltage is a voltage drop of a diode.         The unidirectional isolated multi-stage DC-DC power conversion device according to item 1 of the scope of the patent application, wherein the selection circuit includes a power electronic switch and a diode, and the power electronic switch is connected to the first of the selection circuit. Between an input terminal and an output terminal of the selection circuit.         The unidirectional isolated multi-stage DC-DC power conversion device according to item 5 of the scope of patent application, wherein the anode of the diode is connected to the second input terminal of the selection circuit, and the cathode of the diode is connected to Output terminal of the selection circuit.         The unidirectional isolated multi-stage DC-DC power conversion device according to item 1 of the scope of patent application, wherein the power electronic switch of the selection circuit is controlled by operation, so that the output voltage of the selection circuit can be the first output DC voltage And the sum of the second output DC voltage or only the subtraction of the second output DC voltage and the voltage drop voltage, so as to output two voltage levels to form a multi-stage output voltage, and output a DC voltage through the filter circuit .         The unidirectional isolated multi-stage DC-DC power conversion device according to item 1 of the scope of the patent application, wherein the filter circuit includes an inductor and a capacitor.         A unidirectional isolated multi-stage DC-DC power conversion method includes: providing an inverter, a high-frequency transformer with three windings, a first full-wave rectifier, a second full-wave rectifier, a selection circuit, and A filter circuit, and the selection circuit has a first input terminal, a second input terminal, and an output terminal; the inverter is connected to an input DC voltage source and generates a high-frequency AC voltage with a fixed pulse width ; The primary side of the high frequency transformer with three windings has a first winding, the first winding of the primary side of the high frequency transformer with three windings is connected to an AC output terminal of the inverter, and the three The secondary side of the winding high-frequency transformer has a second winding and a third winding; the input of the first full-wave rectifier is connected to the second winding of the secondary side of the high-frequency transformer with three windings, and the The first full-wave rectifier has a first DC positive output terminal and a first DC negative output terminal, and the first DC positive output terminal and the first DC negative output terminal are connected in parallel to a first capacitor to form a First output DC voltage The input of the second full-wave rectifier is connected to the third winding on the secondary side of the high-frequency transformer with three windings, and the second full-wave rectifier has a second DC positive output terminal and a second DC negative output Terminal, and the second DC positive output terminal and the second DC negative output terminal are connected in parallel with a second capacitor to form a second output DC voltage, and the second DC positive output terminal of the second full-wave rectifier is connected to the first A first DC negative output terminal of a full-wave rectifier; a first input terminal of the selection circuit is connected to a first DC positive output terminal of the first full-wave rectifier, and a second input terminal of the selection circuit is connected A first DC negative output terminal of the first full-wave rectifier and a second DC positive output terminal of the second full-wave rectifier; and connecting the filter circuit to the output terminal of the selection circuit and the second full-wave rectifier A second negative DC output terminal; the selection circuit is controlled by operation, so that the output voltage of the selection circuit is the sum of the first output DC voltage and the second output DC voltage, or a single second output DC voltage and a Press The subtraction of the voltage drops to output two voltage levels to form a multi-stage output voltage, and the DC voltage is output through the filter circuit.         The unidirectional isolated multi-stage DC-DC power conversion method according to item 9 of the scope of the patent application, wherein the voltage drop voltage is a voltage drop voltage of a diode.         The unidirectional isolated multi-stage DC-DC power conversion method according to item 9 of the scope of the patent application, wherein the inverter is selected from a half-bridge inverter or a full-bridge inverter.         The unidirectional isolated multi-stage DC-DC power conversion method according to item 9 of the scope of the patent application, wherein the selection circuit includes a power electronic switch and a diode, and the power electronic switch is connected to the first of the selection circuit. Between an input terminal and an output terminal of the selection circuit.         The unidirectional isolated multi-stage DC-DC power conversion method according to item 12 of the scope of the patent application, wherein the anode of the diode is connected to the second input terminal of the selection circuit, and the cathode of the diode is connected to Output terminal of the selection circuit.         The unidirectional isolated multi-stage DC-DC power conversion method according to item 9 of the scope of the patent application, wherein the power electronic switch of the selection circuit is controlled by operation, so that the output voltage of the selection circuit can be the first output DC voltage And the sum of the second output DC voltage or only the subtraction of the second output DC voltage and the voltage drop voltage, so as to output two voltage levels to form a multi-stage output voltage, and output a DC voltage through the filter circuit .         The unidirectional isolated multi-stage DC-DC power conversion method according to item 9 of the scope of the patent application, wherein the filter circuit includes an inductor and a capacitor.