TWI577123B - Isolated multi-level dc-dc converter and method thereof - Google Patents

Description

Isolated multi-step DC-DC electric energy conversion device and method thereof

The invention relates to an isolated multi-step DC-DC electric energy conversion device and a method thereof; in particular to an isolated multi-step DC-DC electric energy conversion device and method thereof capable of reducing volume; more particularly, a method for reducing output voltage And an isolated multi-step DC-DC power conversion device and method for current ripple.

In general, conventional isolated DC-DC power converters have 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 chopping amount, high electromagnetic interference and large filter capacity required. In contrast, although the conventional multi-step DC-DC power converter has the disadvantages of relatively complicated control, it has relatively high efficiency, relatively small amount of ripple, relatively little electromagnetic interference, and the required use. The advantage of a small filter capacity.

For example, FIG. 1 is a schematic diagram showing the architecture of a conventional multi-step DC-DC power conversion device, which mainly includes four blocks. Referring to FIG. 1 , the conventional multi-step DC-DC power conversion device 1 includes a two-half bridge inverter 11 , a two-frequency transformer 12 , a two-bridge rectifier 13 , and an output filter 14 , which appropriately constitute the Multi-step DC-DC power conversion device 1. In addition, the two-half bridge inverter 11 requires four power switches and four capacitors.

Referring to FIG. 1 again, the power switching operation mode of the two-half bridge type inverter 11 is controlled in the power conversion operation to make the high frequency The primary side of the transformer 12 produces three voltages. Further, the secondary side of the high-frequency transformer 12 is appropriately rectified by the two full-bridge rectifiers 13, and two voltage levels can be output.

However, in practical applications, due to two of the half-bridge inverters The capacitor 11 needs to use four of the capacitors, and the capacitance values of the four capacitors may be different, resulting in inconsistent capacitance voltages of the four capacitors. Therefore, more complicated control is required for control of the inconsistent capacitor voltages of the four capacitors, and two of the high frequency transformers 12 need to be provided. In addition to the possibility that the winding of the high frequency transformer 12 may have errors, the cost of using the two half bridge type inverters 11 and the cost of using the core of the high frequency transformer 12 are relatively increased. In addition, the multi-step DC-DC power conversion device 1 requires the use of two of the high frequency transformers 12 and the two cores, so that the volume thereof is relatively large.

Obviously, the multi-stage DC-DC power converter is used in architecture. There is still a need for technical shortcomings that improve its aforementioned characteristics. Therefore, the conventional DC-DC power converter necessarily has the need to further provide or develop an isolated multi-step DC-DC power converter. The above technical description is only for the purpose of the technical background of the present invention and is not intended to limit the scope of the present invention.

In view of this, the present invention provides for the above needs An isolated multi-step DC-DC electric energy conversion device and method thereof, comprising a half bridge inverter, a three-winding high-frequency transformer, two full-bridge rectifiers, a main power switch, and a first diode a second diode and an output filter, which only use a single half-bridge inverter and a single high-frequency transformer with three windings, and can be achieved by controlling the switching of the main power switch The multi-step switching function to improve the conventional multi-step DC-DC power conversion device requires the technical disadvantages of using two half-bridge inverters and two high-frequency transformers.

The main object of the preferred embodiment of the present invention is to provide a partition Separate multi-step DC-DC electric energy conversion device and method thereof, comprising a half bridge inverter, a three-winding high-frequency transformer, a two-bridge rectifier, a main power switch, a first diode, a second diode and an output filter, which only use a single half-bridge inverter and a single high-frequency transformer with three windings, and can achieve multiple switching by controlling the main power switch The function of the level switching is to achieve the purpose of reducing the volume, reducing the manufacturing cost and simplifying the operation.

In order to achieve the above object, the isolation of the preferred embodiment of the present invention The multi-step DC-DC power conversion device comprises: a half bridge inverter; a high frequency transformer comprising a primary side and a secondary side, the primary side of the high frequency transformer having a first winding, and the high frequency a first winding of the primary side of the transformer is connected to the half-bridge inverter, and a secondary side of the high-frequency transformer has a second winding and a third winding; a first full-bridge rectifier, the input of which is connected to a second winding of the secondary side of the high frequency transformer, and an output of the first full bridge rectifier is connected to a first capacitor to form a first output DC voltage; a second full bridge rectifier having an input connected thereto a third winding of the secondary side of the high frequency transformer, and the output of the second full bridge rectifier is connected to a second capacitor to form a second output DC voltage; a main power switch connected to the first output DC voltage a negative terminal between the negative terminal and the positive terminal of the second output DC voltage; a first diode connected between the positive terminal of the first output DC voltage and the positive terminal of the second output DC voltage; a diode, which is connected to Between the negative terminal of the first output DC voltage and the negative terminal of the second output DC voltage; and an output filter coupled between the positive terminal of the first output DC voltage and the negative terminal of the second output DC voltage .

The preferred embodiment of the present invention utilizes operation to control the main power on Off, the first output DC voltage and the second output DC voltage are formed in series or parallel to output two voltage levels to form a multi-level output voltage, and the output current filter outputs a DC voltage.

The secondary side of the high frequency transformer of the preferred embodiment of the present invention The second winding is connected to the input of the first full bridge rectifier, and the output of the first full bridge rectifier is connected in parallel with the first capacitor to form the first output DC voltage, and the positive end of the first output DC voltage Connected to the cathode of the first diode and the positive terminal of the output filter.

The first output DC voltage of the preferred embodiment of the present invention The negative terminal is connected to the source of the main power switch and the cathode of the second diode.

The secondary side of the high frequency transformer of the preferred embodiment of the present invention a third winding is coupled to the input of the second full bridge rectifier, and an output of the second full bridge rectifier is coupled in parallel with the second capacitor to form the second output DC voltage, and the positive terminal of the second output DC voltage Connected to the anode of the first diode and the drain of the main power switch.

The second output DC voltage of the preferred embodiment of the present invention The negative terminal is connected to the anode of the second diode and the negative terminal of the output filter.

In the preferred embodiment of the present invention, when the main power switch is turned on, the The first output DC voltage is connected in series with the second output DC voltage, and when the main power switch is turned off, the first output DC voltage is connected in parallel with the second output DC voltage.

In order to achieve the above object, the isolation of the preferred embodiment of the present invention The multi-step DC-DC power conversion method comprises: providing a half bridge inverter, a high frequency transformer, a first full bridge rectifier, a second full bridge rectifier, a main power switch, and a first two pole a second diode and an output filter; the 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 half bridge inverter And the second side of the high frequency transformer has a second winding and a third winding; the first full bridge rectifier is connected to the second winding of the secondary side of the high frequency transformer, and the first full bridge The output of the rectifier is connected to a first capacitor to form a first output DC voltage; the second full bridge rectifier is connected to the third winding of the secondary side of the high frequency transformer, and the output of the second full bridge rectifier Connecting a second capacitor to form a second output DC voltage; connecting the main power switch between the negative terminal of the first output DC voltage and the positive terminal of the second output DC voltage; The body is connected between the positive terminal of the first output DC voltage and the positive terminal of the second output DC voltage; the second diode is connected to the negative terminal of the first output DC voltage and the negative of the second output DC voltage Between the terminals; and connecting the output filter between the positive terminal of the first output DC voltage and the negative terminal of the second output DC voltage; wherein the main power switch is controlled by operation to make the first output DC voltage and Second output straight Voltage in series or parallel are formed so as to output two kinds of voltage levels to form a multi-level output voltage, and outputs the filter output via a DC voltage.

The secondary side of the high frequency transformer of the preferred embodiment of the present invention The second winding is connected to the input of the first full bridge rectifier, and the output of the first full bridge rectifier is connected in parallel with the first capacitor to form the first output DC voltage, and the positive end of the first output DC voltage Connected to the cathode of the first diode and the positive terminal of the output filter.

The first output DC voltage of the preferred embodiment of the present invention The negative terminal is connected to the source of the main power switch and the cathode of the second diode.

The secondary side of the high frequency transformer of the preferred embodiment of the present invention a third winding is coupled to the input of the second full bridge rectifier, and an output of the second full bridge rectifier is coupled in parallel with the second capacitor to form the second output a DC voltage, and a positive end of the second output DC voltage is coupled to the anode of the first diode and the drain of the main power switch.

In a preferred embodiment of the invention, the negative terminal of the second output DC voltage is connected to the anode of the second diode and the negative terminal of the output filter.

1‧‧‧Multi-step DC-DC power conversion device

11‧‧‧Half-bridge inverter

12‧‧‧High frequency transformer

13‧‧‧ Full Bridge Rectifier

14‧‧‧Output filter

2‧‧‧Isolated multi-step DC-DC power conversion device

21‧‧‧Half-bridge inverter

210‧‧‧Multi-level output voltage

C ₁ ‧‧‧ capacitor

C ₂ ‧‧‧ capacitor

S _dc1 ‧‧‧ power switch

S _dc2 ‧‧‧ power switch

22‧‧‧High frequency transformer

N _p ‧‧‧first winding

N _s1 ‧‧‧second winding

N _s2 ‧‧‧third winding

23‧‧‧First full bridge rectifier

D ₁ ‧‧‧ diode

D ₂ ‧‧‧ diode

D ₃ ‧‧‧dipole

D ₄ ‧‧‧ diode

24‧‧‧Second full bridge rectifier

D ₅ ‧‧‧ diode

D ₆ ‧‧‧ diode

D ₇ ‧‧‧ diode

D ₈ ‧‧‧ diode

25‧‧‧ main power switch

261‧‧‧First capacitor

262‧‧‧second capacitor

271‧‧‧First Diode

272‧‧‧second diode

28‧‧‧Output filter

281‧‧‧Inductance

282‧‧‧ capacitor

29‧‧‧Input DC voltage

211‧‧‧ Output DC voltage

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

2 is a schematic view showing the architecture of an isolated multi-step DC-DC power conversion device according to a preferred embodiment of the present invention.

3(A) to 3(C): The control method of the isolated multi-step DC-DC power conversion device according to the preferred embodiment of the present invention adopts a waveform diagram of each power switching signal and its multi-stage output voltage.

Figure 4(A): The isolated multi-step DC-DC power conversion device of the preferred embodiment of the present invention uses a power switch on the half-bridge inverter to turn on, and the power switch and the main under the half-bridge inverter The equivalent circuit diagram of the power switch cutoff.

Figure 4(B): The isolated multi-step DC-DC power conversion device of the preferred embodiment of the present invention uses a power switch and a main power switch on the half-bridge inverter, and the half-bridge inverter The equivalent circuit diagram of the power switch cutoff.

Figure 4 (C): The isolated multi-step DC-DC power conversion device of the preferred embodiment of the present invention uses a power switch under the half-bridge inverter, and the power switch and the main switch on the half-bridge inverter The equivalent circuit diagram of the power switch cutoff.

Figure 4(D): The isolated multi-step DC-DC power conversion device of the preferred embodiment of the present invention uses a power switch and a main power switch under the half-bridge inverter, and the half-bridge inverter is above The equivalent circuit diagram of the power switch cutoff.

In order to fully understand the present invention, the preferred embodiments of the present invention are described in detail below, and are not intended to limit the invention.

The isolated multi-step DC-DC power conversion device and method thereof according to the preferred embodiment of the present invention are applicable to various multi-stage power conversion devices or the like, but are not intended to limit the scope of the present invention.

FIG. 2 is a block diagram showing the structure of an isolated multi-step DC-DC power conversion device according to a preferred embodiment of the present invention. Referring to FIG. 2, the isolated multi-step DC-DC power conversion device 2 of the preferred embodiment of the present invention comprises a half bridge inverter 21, a high frequency transformer 22, a first full bridge rectifier 23, A second full bridge rectifier 24, a main power switch 25, a first diode 271, a second diode 272, and an output filter 28. The half-bridge inverter 21 includes two capacitors C ₁ , C ₂ , an upper power switch (or first power switch) S _dc1 and a lower power switch (or second power switch) S _dc2 . The input terminal of the half-bridge inverter 21 is connected in parallel with an input DC voltage V _in 29 . The high-frequency transformer 22 includes a primary side and a secondary side, and the primary side of the high-frequency transformer 22 is appropriately connected to the alternating current end of the half-bridge inverter 21. The primary side of the high-frequency transformer 22 has a first winding N _p , and the second side of the high-frequency transformer 22 has a second winding N _s1 and a third winding N _s2 to form a three-winding high. Frequency transformer. The output filter 28 is selected from an LC filter or other filter.

Referring again to FIG. 2, for example, the first full bridge rectifier 23 includes four diodes D ₁ , D ₂ , D ₃ , and D ₄ . The input of the first full bridge rectifier 23 is connected to the second winding N _s1 of the secondary side of the high frequency transformer 22, and the output of the first full bridge rectifier 23 is connected to a first capacitor 261 to form a first An output DC voltage is coupled to the positive terminal of the first diode 271 and the positive terminal of the output filter 28.

Referring again to FIG. 2, for example, the second full bridge rectifier 24 includes four diodes D ₅ , D ₆ , D ₇ , and D ₈ . The input of the second full bridge rectifier 24 is connected to the third winding N _s2 of the secondary side of the high frequency transformer 22, and the output of the second full bridge rectifier 24 is connected to a second capacitor 262 to form a first The output DC voltage is connected, and the negative terminal of the second output DC voltage is connected to the anode of the second diode 272 and the negative terminal of the output filter 28.

Please refer to Figure 2 again, for example, the main power The switch 25 is connected in series between the negative terminal of the first output DC voltage and the positive terminal of the second output DC voltage. That is, the negative terminal of the first output DC voltage is selected to be connected to the source of the main power switch 25 and to the cathode of the second diode 272. Additionally, the positive terminal of the second output DC voltage is coupled to the drain of the main power switch 25 and to the anode of the first diode 271. At the same time, the output filter 28 is connected to the positive terminal of the first output DC voltage and the negative terminal of the second output DC voltage.

Please refer to Figure 2 again, for example, using operational controls. The main power switch 25 is configured to form a second output DC voltage of the first output DC voltage in series or parallel to output two voltage levels to form a multi-level output voltage 210, and output an output via the output filter 28. The DC voltage 211 is shown on the right side of Figure 2.

3(A) to 3(C) are diagrams showing a control method of an isolated multi-step DC-DC power conversion device according to a preferred embodiment of the present invention, which uses waveform diagrams of respective power switching signals and multi-level output voltages thereof, which corresponds to Figure 2 is an isolated multi-step DC-DC power conversion device. Referring to Figures 2, 3(A) and 3(B), the switching signals of the power switch S _dc1 and the lower power switch S _dc2 on the half-bridge inverter 21 are disclosed in Figure 3(A). The switching signal of the main power switch 25 is disclosed in Figure 3(B). For example, the switching frequency of the switching signal of the main power switch 25 is selected to be twice or other multiples of the switching frequency of the switching signals of the power switch S _dc1 and the lower power switch S _dc2 on the half bridge inverter 21, As shown in Figures 3(A) and 3(B).

Referring to FIGS. 2 and 3(A) to 3(C), since the main power switch 25 is controlled by the high frequency switching operation, the first output DC voltage and the second output DC voltage are connected in series or in parallel. The multi-level output voltage 210 is formed by outputting two voltage levels, as shown in FIG. 3(C). Finally, the multi-level output voltage 210 outputs the output DC voltage 211 via the output filter 28. In operation, when the main power switch 25 is turned on, the voltage of the waveform of the multi-level output voltage 210 is V _in / n ; conversely, when the main power switch 25 is turned off, the voltage of the waveform of the multi-level output voltage 210 is V _In / 2n , the function of outputting the multi-level voltage level can be achieved; where n is the turns ratio of the primary side and the secondary side winding of the high-frequency transformer 22, and the second winding of the secondary side of the high-frequency transformer 22 N _s1 and the third winding N _s2 have the same number of turns.

FIG. 4(A) shows that the isolated multi-step DC-DC power conversion device of the preferred embodiment of the present invention uses a power switch S _dc1 on the half-bridge inverter to be turned on, and the power switch under the half-bridge inverter Schematic diagram of the equivalent circuit of S _dc2 and main power switch cutoff. Referring to FIG. 4(A), the power switch S _dc1 on the half bridge inverter 21 is turned on, and the power switch S _dc2 and the main power switch 25 are turned off under the half bridge inverter 21 . At this time, the primary side current of the high frequency transformer 22 flows out from the positive terminal of the capacitor C ₁ of the half bridge type inverter 21, and the power switch S _dc1 and the high frequency transformer 22 pass through the half bridge type inverter 21 The negative terminal of the capacitor C ₁ of the half bridge inverter 21 forms a loop. At this time, the black point end of the primary side of the high frequency transformer 22 is a negative voltage, and the non-black point end of the primary side of the high frequency transformer 22 is a positive voltage.

Referring again to FIG. 4(A), a first secondary current flows from a non-black point end of the second winding N _s1 of the secondary side of the high frequency transformer 22, through the first full bridge rectifier. a diode D ₃ , a first capacitor 261, a diode D _{2 of the} first full bridge rectifier 23, and a black point end of the second winding N _s1 of the secondary side of the high frequency transformer 22 form a loop to A first DC voltage is generated. Since the main power switch 25 is turned off, the positive terminal of the first DC voltage is connected to the positive terminal of the output filter 28, and the negative terminal of the first DC voltage is connected to the output filter via the second diode 272. The negative end of the device 28.

Referring to FIG. 4(A) again, a second secondary current flows from the non-black point end of the third winding N _s2 on the secondary side of the high frequency transformer 22, and the second full bridge rectifier is passed through the second full-bridge rectifier. 24 of the diode D _7, a second capacitor 262, a second full bridge rectifier 24 of diode D _6, 22 of the second black dot terminal side of the third winding of the high-frequency transformer N _s2 form another loop, To generate a second DC voltage. Since the main power switch 25 is turned off, the negative terminal of the second DC voltage is connected to the negative terminal of the output filter 28, and the positive terminal of the second DC voltage is connected to the output filter via the first diode 271. The positive end of the device 28. At this time, the first DC voltage and the second DC voltage of the high frequency transformer 22 are operated in a parallel mode, and the multi-step output voltage 210 is V _in / 2n .

FIG. 4(B) shows that the isolated multi-step DC-DC power conversion device of the preferred embodiment of the present invention uses a power switch S _dc1 and a main power switch on the half bridge inverter, and the half bridge inverter The equivalent circuit diagram of the power switch S _dc2 cutoff. Referring to FIG. 4(B), the power switch S _dc1 and the main power switch 25 on the half bridge inverter 21 are turned on, and the power switch S _dc2 under the half bridge inverter 21 is turned off. . At this time, the voltage of the high frequency transformer 22 remains unchanged, and a first secondary side current flows out from the non-black point end of the second winding N _s1 on the secondary side of the high frequency transformer 22, via the first full bridge. The diode D _{3 of the} rectifier 23, the first capacitor 261, the diode D _{2 of the} first full bridge rectifier 23, and the black terminal of the second winding N _s1 on the secondary side of the high frequency transformer 22 form a loop To generate a first DC voltage.

Referring to FIG. 4(B) again, a second secondary current flows out from the non-black point end of the third winding N _s2 on the secondary side of the high frequency transformer 22, and the second full bridge rectifier is passed through the second full-bridge rectifier. 24 of the diode D _7, a second capacitor 262, a second full bridge rectifier 24 of diode D _6, the high frequency transformer 22 the secondary side of the black dot end of the third winding N _s2 of forming a loop to A second DC voltage is generated. Since the main power switch 25 is turned on, the first DC voltage and the second DC voltage are connected in series via the main power switch 25. In contrast, at this time, the multi-level output voltage 210 is V _in / n and is filtered by the output filter 28.

4(C) shows that the isolated multi-step DC-DC power conversion device of the preferred embodiment of the present invention uses a power switch S _dc2 under the half-bridge inverter to be turned on, and the power switch above the half-bridge inverter Schematic diagram of the equivalent circuit of S _dc1 and main power switch cutoff. Referring to FIG. 4(C), the power switch S _dc2 under the half bridge inverter 21 is turned on, and the power switch S _dc1 and the main power switch 25 are turned off on the half bridge inverter 21 . . The primary side current flows out from the positive terminal of the capacitor C ₂ of the half bridge inverter 21, and the negative end of the power switch S _dc2 and the capacitor C ₂ under the high frequency transformer 22 and the half bridge inverter 21 form a Loop. At this time, the black point end of the high frequency transformer 22 is a positive voltage, and the non-black point end of the high frequency transformer 22 is a negative voltage.

Referring to FIG. 4(C) again, a first secondary current flows out from the black point end of the second winding N _s1 on the secondary side of the high frequency transformer 22, and passes through the first full bridge rectifier 23 . The diode D ₁ , the first capacitor 261, the diode D _{4 of the} first full bridge rectifier 23, and the non-black dot end of the second winding N _s1 of the secondary side of the high frequency transformer 22 form a loop to A first DC voltage is generated. Since the main power switch 25 is turned off, the positive terminal of the first DC voltage is connected to the positive terminal of the output filter 28, and the negative terminal of the first DC voltage is connected to the output filter via the second diode 272. The negative end of the device 28.

Referring to FIG. 4(C) again, a second secondary current flows from the black point end of the third winding N _s2 on the secondary side of the high frequency transformer 22, and passes through the second full bridge rectifier 24 . The diode D ₅ , the second capacitor 262 , the diode D _{8 of the} second full bridge rectifier 24 , and the non-black dot end of the third winding N _s2 of the secondary side of the high frequency transformer 22 form a loop to A second DC voltage is generated. Since the main power switch 25 is turned off, the negative terminal of the second DC voltage is connected to the negative terminal of the output filter 28, and the positive terminal of the second DC voltage is connected to the output filter via the first diode 271. The positive end of the device 28. At this time, the first DC voltage and the second DC voltage are operated in a parallel mode, and the multi-step output voltage 210 is V _in / 2n .

FIG. 4(D) shows that the isolated multi-step DC-DC power conversion device of the preferred embodiment of the present invention uses a power switch S _dc2 under the half bridge inverter and the main power switch is turned on, and the half bridge inverter An equivalent circuit diagram of the power switch S _dc1 off. Referring to FIG. 4(D), the power switch S _dc2 and the main power switch 25 under the half bridge inverter 21 are turned on, and the power switch S _{dc1 is} turned off on the half bridge inverter 21 . At this time, the voltage of the high frequency transformer 22 remains unchanged, and a first secondary side current flows out from the black point end of the second winding N _s1 on the secondary side of the high frequency transformer 22, and the first full bridge type The diode D _{1 of the} rectifier 23, the first capacitor 261, the diode D _{4 of the} first full bridge rectifier 23 and the non-black point of the second winding N _s1 on the secondary side of the high frequency transformer 22 form a loop To generate a first DC voltage.

Referring to FIG. 4(D) again, a second secondary current flows from the black point end of the third winding N _s2 on the secondary side of the high frequency transformer 22, and the second full bridge rectifier 24 passes through the second full-side rectifier 24 . The diode D ₅ , the second capacitor 262 , the diode D _{8 of the} second full bridge rectifier 24 , and the non-black dot end of the third winding N _s2 of the secondary side of the high frequency transformer 22 form a loop to A second DC voltage is generated. Since the main power switch 25 is turned on, the first DC voltage and the second DC voltage are connected in series via the main power switch 25. In contrast, at this time, the multi-level output voltage 210 is V _in / n and is filtered by the output filter 28.

The foregoing preferred embodiments are merely illustrative of the invention and its techniques It is to be understood that the scope of the present invention is to be construed as being limited by the scope of the appended claims. The copyright limitation of this case is used for the purpose of patent application in the Republic of China.

2‧‧‧Isolated multi-step DC-DC power conversion device

21‧‧‧Half-bridge inverter

210‧‧‧Multi-level output voltage

C ₁ ‧‧‧ capacitor

C ₂ ‧‧‧ capacitor

S _dc1 ‧‧‧ power switch

S _dc2 ‧‧‧ power switch

22‧‧‧High frequency transformer

N _p ‧‧‧first winding

N _s1 ‧‧‧second winding

N _s2 ‧‧‧third winding

23‧‧‧First full bridge rectifier

D ₁ ‧‧‧ diode

D ₂ ‧‧‧ diode

D ₃ ‧‧‧dipole

D ₄ ‧‧‧ diode

24‧‧‧Second full bridge rectifier

D ₅ ‧‧‧ diode

D ₆ ‧‧‧ diode

D ₇ ‧‧‧ diode

D ₈ ‧‧‧ diode

25‧‧‧ main power switch

261‧‧‧First capacitor

262‧‧‧second capacitor

271‧‧‧First Diode

272‧‧‧second diode

28‧‧‧Output filter

281‧‧‧Inductance

282‧‧‧ capacitor

29‧‧‧Input DC voltage

211‧‧‧ Output DC voltage

Claims (10)

An isolated multi-step DC-DC power conversion device comprising: a half bridge inverter; a high frequency transformer comprising a primary side and a secondary side, and the primary side of the high frequency transformer has a first winding, And the second side of the high frequency transformer has a second winding and a third winding, and the first winding of the primary side of the high frequency transformer is connected to the half bridge inverter; a first full bridge rectifier The input is connected to the second winding of the secondary side of the high frequency transformer, and the output of the first full bridge rectifier is connected to a first capacitor to form a first output DC voltage; a second full bridge rectifier, The input is connected to the third winding of the secondary side of the high frequency transformer, and the output of the second full bridge rectifier is connected to a second capacitor to form a second output DC voltage; a main power switch connected to the a negative terminal of the first output DC voltage and a positive terminal of the second output DC voltage; a first diode connected to the positive terminal of the first output DC voltage and the positive terminal of the second output DC voltage Between a diode connected between the negative terminal of the first output DC voltage and a negative terminal of the second output DC voltage; and an output filter connected to the positive terminal of the first output DC voltage and the second Between the negative ends of the output DC voltage. The isolated multi-step DC-DC power conversion device according to claim 1, wherein the second winding of the secondary side of the high frequency transformer is connected to the input of the first full bridge rectifier, and the first full The output of the bridge rectifier is connected in parallel with the first capacitor to form the first output DC voltage, and the positive terminal of the first output DC voltage is connected to the cathode of the first diode and the positive terminal of the output filter. The isolated multi-step DC-DC power conversion device according to claim 1, wherein a negative end of the first output DC voltage is connected to a source of the main power switch and a cathode of the second diode. The isolated multi-step DC-DC power conversion device according to claim 1, wherein the third winding of the secondary side of the high frequency transformer is connected to the input of the second full bridge rectifier, and the second full The output of the bridge rectifier is connected in parallel with the second capacitor to form the second output DC voltage, and the positive terminal of the second output DC voltage is connected to the anode of the first diode and the drain of the main power switch. The isolated multi-step DC-DC power conversion device according to claim 1, wherein the negative end of the second output DC voltage is connected to the anode of the second diode and the negative terminal of the output filter. An isolated multi-step DC-DC power conversion method includes: providing a half bridge inverter, a high frequency transformer, a first full bridge rectifier, a second full bridge rectifier, a main power switch, and a a first diode, a second diode, and an output filter; the primary side of the high frequency transformer is connected to the half bridge inverter, and the primary side of the high frequency transformer has a first winding, And the second side of the high frequency transformer has a second winding and a third winding; the input of the first full bridge rectifier is connected to the secondary side of the high frequency transformer, and the first full bridge rectifier The output is connected to a first capacitor to form a first output DC voltage; the input of the second full bridge rectifier is connected to the secondary side of the high frequency transformer, and the output of the second full bridge rectifier is connected to a second Forming a second output DC voltage by the capacitor; connecting the main power switch between the negative terminal of the first output DC voltage and the positive terminal of the second output DC voltage; connecting the first diode to the first An output DC voltage a positive terminal and a positive terminal of the second output DC voltage; the second diode is coupled between the negative terminal of the first output DC voltage and the negative terminal of the second output DC voltage; and the output a filter is connected between the positive terminal of the first output DC voltage and the negative terminal of the second output DC voltage; The operation of controlling the half-bridge inverter and the main power switch to form the first output DC voltage output voltage and the second output DC voltage in series or parallel to output two voltage levels to form a multi-level output voltage And output the current through the output filter. According to the method of claim 6, the isolated multi-step DC-DC power conversion method, wherein the second winding of the secondary side of the high frequency transformer is connected to the input of the first full bridge rectifier, and the first full The output of the bridge rectifier is connected in parallel with the first capacitor to form the first output DC voltage, and the positive terminal of the first output DC voltage is connected to the cathode of the first diode and the positive terminal of the output filter. The isolated multi-step DC-DC power conversion method according to claim 6 , wherein a negative end of the first output DC voltage is connected to a source of the main power switch and a cathode of the second diode. According to the method of claim 6, the isolated multi-step DC-DC power conversion method, wherein the third winding of the secondary side of the high frequency transformer is connected to the input of the second full bridge rectifier, and the second full The output of the bridge rectifier is connected in parallel with the second capacitor to form the second output DC voltage, and the positive terminal of the second output DC voltage is connected to the anode of the first diode and the drain of the main power switch. The isolated multi-step DC-DC power conversion method according to claim 6, wherein the negative end of the second output DC voltage is connected to the anode of the second diode and the negative end of the output filter.