CN207039460U - A kind of double tube positive exciting type Z sources DC voltage converter - Google Patents

Abstract

The utility model discloses a kind of double tube positive exciting type Z sources DC voltage converter, including first voltage source, the second voltage source, tertiary voltage source, the 4th voltage source, the 5th voltage source, the first electric capacity, the second electric capacity, first switch pipe, second switch pipe, the first diode, the second diode, the 3rd diode, the 4th diode, inductance, load and transformer, wherein the first winding of the transformer is as primary side, and the second winding is as secondary.The utility model uses the structure of two-transistor forward converter, the advantages of having two-transistor forward converter and Z source converters concurrently simultaneously, i.e. circuit is simple, cost is low, reliability is high, drive circuit is simple etc., and the voltage for realizing input and outlet side well is isolated, be advantageous to the electric insulation of equipment, outlet side voltage x current ripple is small, while higher voltage gain can be realized in low duty ratio, realizes multi input.

Description

A dual-transistor forward Z-source DC voltage converter

technical field

The utility model relates to the technical field of power electronic converters, in particular to a dual-tube forward type Z-source DC voltage converter.

Background technique

High-efficiency DC power conversion technology is one of the key research areas of modern power electronics technology, and the basic DC converter topology as the skeleton fundamentally supports the DC power conversion technology.

As a small and medium power switching power supply, the dual-transistor forward converter has the characteristics of simple circuit structure, convenient control mode, and electrical isolation between input and output. It has a great application in isolated occasions that require high safety and insulation. However, the dual-transistor forward converter is a derivative topology of the Buck converter. In order to ensure the reset of the magnetic core and prevent the saturation of the excitation inductance, the actual operating duty cycle is less than 0.5, which further reduces the gain of the output voltage.

Although Z-source converters, quasi-Z-source converters, and transformer-based Z-source converters proposed in recent years can all achieve a large increase in output voltage gain when the duty cycle is less than 0.5, they cannot realize the input and output. Electrical isolation severely limits the application occasions of the Z-source series topology.

Contents of the invention

The purpose of the utility model is to overcome the deficiencies and shortcomings of the prior art, and provide a dual-tube forward type Z-source DC voltage converter, which is suitable for power electronic circuits requiring high gain and isolation.

In order to achieve the above purpose, the technical solution provided by the utility model is: a dual-transistor forward type Z-source DC voltage converter, including a first voltage source, a second voltage source, a third voltage source, a fourth voltage source, Fifth voltage source, first capacitor, second capacitor, first switch tube, second switch tube, first diode, second diode, third diode, fourth diode, inductor, load and a transformer; the first winding of the transformer is used as the primary side of the transformer, and the second winding is used as the secondary side of the transformer; the anode of the first capacitor is respectively connected to the drain of the first switching tube and the cathode of the second diode ; The negative pole of the first capacitor is respectively connected to the source of the second switching tube and the anode of the first diode; the negative pole of the first voltage source is connected to the source of the first switching tube, and its positive pole is respectively connected to the first switching tube. The negative pole of the three voltage sources is connected to the positive pole of the fourth voltage source; the negative pole of the fourth voltage source is connected to the cathode of the first diode; the positive pole of the third voltage source is connected to the terminal with the same name of the first winding; The positive pole of the fifth voltage source is connected to the anode of the second diode, and its negative pole is respectively connected to the negative pole of the second voltage source and the opposite end of the first winding; the same end of the second winding is connected to the third diode The anode of the tube is connected, and its opposite end is respectively connected with the anode of the fourth diode, the negative pole of the second capacitor and one end of the load; the cathode of the third diode is respectively connected with the cathode of the fourth diode and the inductance One end of the inductance is connected; the other end of the inductor is respectively connected to the positive pole of the second capacitor and the other end of the load.

Wherein, in the case of a single input, the Z-source DC voltage converter only needs one power supply, and the other power supplies are short-circuited or the input value is zero, that is, the first power supply, the second power supply, the third power supply, the fourth power supply and the fourth power supply Any one of the five power supplies is reserved as an input, while the other four power supplies are short-circuited or the input value is zero; similarly, in the case of dual inputs, the Z source DC voltage converter only needs two power supplies, and the other four power supplies are short-circuited. connected or the input value is zero, that is, any two of the first power supply, the second power supply, the third power supply, the fourth power supply and the fifth power supply are reserved as inputs, while the other three power supplies are short-circuited or the input value is zero; Theoretically, in the case of three inputs, the Z-source DC voltage converter only needs three power supplies, and the other power supplies are short-circuited or the input value is zero, that is, the first power supply, the second power supply, the third power supply, the fourth power supply and Any three power supplies are reserved as inputs in the fifth power supply, while the other two power supplies are short-circuited or the input value is zero; similarly, in the case of four inputs, the Z source DC voltage converter only needs four power supplies, and the other The power supply is short-circuited or the input value is zero, that is, any four power supplies of the first power supply, the second power supply, the third power supply, the fourth power supply and the fifth power supply are reserved as inputs, while the other power supplies are short-circuited or the input value is zero; Theoretically, in the case of five inputs, the first power supply, the second power supply, the third power supply, the fourth power supply and the fifth power supply of the Z-source DC voltage converter are reserved.

The first voltage source and the first switching tube are sequentially connected in series to form a branch circuit. In the same branch circuit, the positions of the first voltage source and the first switching tube can be exchanged, but according to the flow direction of the current, the first voltage source must be The anode of the first switching tube is connected in series with the drain of the first switching tube, or the source of the first switching tube is connected in series with the negative terminal of the first voltage source.

The second voltage source and the second switching tube are sequentially connected in series to form a branch. In the same branch, the positions of the second voltage source and the second switching tube can be exchanged, but according to the flow direction of the current, the second voltage source must be The anode of the second switching tube is connected in series with the drain of the second switching tube, or the source of the second switching tube is connected in series with the negative terminal of the second voltage source.

The third voltage source and the first winding are sequentially connected in series to form a branch. In the same branch, the positions of the third voltage source and the first winding can be exchanged, but according to the flow direction of the current, it must be the positive pole of the third voltage source. The same-named end of the first winding is connected in series, or the negative electrode of the third voltage source is connected in series with the different-named end of the first winding.

The fourth voltage source and the first diode are sequentially connected in series to form a branch. In the same branch, the positions of the fourth voltage source and the first diode can be exchanged, but according to the flow direction of the current, it must be the fourth The anode of the first diode is connected in series with the anode of the voltage source, or the cathode of the first diode is connected in series with the cathode of the fourth voltage source.

The fifth voltage source and the second diode are sequentially connected in series to form a branch. In the same branch, the positions of the fifth voltage source and the second diode can be exchanged, but the current flow must be the fifth The anode of the voltage source is connected in series with the anode of the second diode, or the cathode of the second diode is connected in series with the cathode of the fifth voltage source.

The transformer may use a multi-winding transformer, and its multiple secondary windings are used as output windings to realize multiple load outputs.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

1. The utility model adopts the structure of the double-tube forward converter, and has the advantages of the double-tube forward converter and the Z-source converter at the same time, specifically, the circuit is simple, the cost is low, the reliability is high, and the driving circuit is simple.

2. The voltage isolation between the input and output sides is realized, which is beneficial to the electrical insulation of the equipment, and the voltage and current ripple on the output side is small.

3. High voltage gain can be realized at low duty cycle, and multiple inputs can be realized.

Description of drawings

Fig. 1 is a circuit diagram of the dual-tube forward type Z-source DC voltage converter described in the present invention.

Fig. 2a, Fig. 2b are respectively the two-tube forward type Z-source dc voltage converter described in the utility model in the first switching tube S ₁ and the second switching tube S ₂ conduction and shut-off in two main phases etc. Effective circuit diagram. The solid line in the figure indicates the part where current flows in the converter, and the dotted line indicates the part where no current flows in the converter.

Fig. 3 is the emulation main working waveform diagram of the circuit of the utility model.

detailed description

Below in conjunction with specific embodiment the utility model is further described.

Referring to Figure 1, the dual-transistor forward Z-source DC voltage converter provided in this embodiment includes a first voltage source V _i1 , a second voltage source V _i2 , a third voltage source V _i3 , and a fourth voltage source V _i4 , fifth voltage source V _i5 , first capacitor C ₁ , second capacitor C ₂ , first switch tube S ₁ , second switch tube S ₂ , first diode D ₁ , second diode D _2. The third diode D ₃ , the fourth diode D ₄ , the inductor L, the load R and the transformer T; the first winding W ₁ of the transformer T is used as the primary side of the transformer T, and the second winding W ₂ is used as the primary side of the transformer T. The secondary side of the transformer T; the anode of the first capacitor _C1 is respectively connected to the drain of the _first switching tube S1 and the cathode of the second diode D2 _; the cathode of the first capacitor _C1 is respectively connected to the second The source of the _second switching tube S2 is connected to the anode of the _first diode D1; the negative pole of the first voltage source V _i1 is connected to the source of the _first switching tube S1, and its positive pole is respectively connected to the third voltage source The negative pole of V _i3 is connected to the positive pole of the fourth voltage source V _{i4; the negative pole of the fourth voltage source V i4 is} connected to the cathode of the _first diode D1; the positive pole of the third voltage source V _i3 is connected to the first diode D1. The terminal with the same name _of the winding W1 is connected; the anode of the fifth voltage source V _i5 is connected to the anode of the _second diode D2, and its cathode is respectively connected to the negative pole of the second voltage source V _i2 and the pole of the _first winding W1. The same-named end of the _second winding W2 is connected to the anode of the third diode _D3 , and its different-named end is connected to the anode of the _fourth diode D4, the negative electrode of the _second capacitor C2 and the anode of the third diode D3 respectively. One end of the load R is connected; the cathode of the third diode _D3 is respectively connected to the cathode of the _fourth diode D4 and one end of the inductance L; the other end of the inductance L is respectively connected to the _second capacitor C2 The positive pole is connected to the other end of the load R.

Wherein, in the case of a single input, the Z-source DC voltage converter only needs one power supply, and other power supplies are short-circuited or the input value is zero, that is, the first power supply V _i1 , the second power supply V _i2 , and the third power supply V _i3 , the fourth power supply V _i4 and the fifth power supply V _i5 retain any power supply as an input, while the other four power supplies are short-circuited or the input value is zero; similarly, in the case of double input, the Z source DC voltage conversion The _converter only needs two power _supplies , and the other power _supplies are _short - _circuited or the input value is zero, that is, any Two power supplies are used as inputs, while the other three power supplies are short-circuited or the input value is zero; similarly, in the case of three inputs, the Z-source DC voltage converter only needs three power supplies, and the other power supplies are short-circuited or the input value is zero. is zero, that is, any three of the first power V _i1 , the second power V _i2 , the third power V _i3 , the fourth power V _i4 and the fifth power V _i5 are reserved as inputs, while the other two power sources are short-circuited or The input value is zero; similarly, in the case of four inputs, the Z-source DC voltage converter only needs four power supplies, and other power supplies are short-circuited or the input value is zero, that is, the first power supply V _i1 , the second power supply V _i2 , the third power supply V _i3 , the fourth power supply V _i4 and the fifth power supply V _i5 reserve any four power supplies as inputs, while the other power supplies are short-circuited or the input value is zero; similarly, in the case of five inputs, all The first power source V _i1 , the second power source V _i2 , the third power source V _i3 , the fourth power source V _i4 and the fifth power source V _i5 of the Z-source DC voltage converter are reserved.

The first voltage source V _i1 and the _first switch tube S1 are sequentially connected in series to form a branch. In the same branch, the positions of the first voltage source V _i1 and the _first switch tube S1 can be exchanged, but according to the current The flow direction must be that the anode of the first voltage source V _i1 is connected in series with the drain of the first switching transistor S ₁ , or the source of the first switching transistor S ₁ is connected in series with the negative electrode of the first voltage source V _i1 .

The second voltage source V _i2 and the _second switch tube S2 are sequentially connected in series to form a branch. In the same branch, the positions of the second voltage source V _i2 and the _second switch tube S2 can be exchanged, but according to the current The flow direction must be that the anode of the second voltage source V _i2 is connected in series with the drain of the second switching transistor S ₂ , or the source of the second switching transistor S ₂ is connected in series with the negative electrode of the second voltage source V _i2 .

The third voltage source V _i3 and the first winding W ₁ are sequentially connected in series to form a branch. In the same branch, the positions of the third voltage source V _i3 and the first winding W ₁ can be exchanged, but according to the flow direction of the current It must be that the anode of the third voltage source V _i3 is connected in series with the terminal with the same name of the first winding W ₁ , or the terminal with the same name of the first winding W ₁ is connected in series with the negative terminal of the third voltage source V _i3 .

The fourth voltage source V _i4 and the first diode D ₁ are sequentially connected in series to form a branch, and in the same branch, the positions of the fourth voltage source V _i4 and the first diode D ₁ can be exchanged, but Depending on the direction of current flow, the anode of the fourth voltage source V _i4 must be connected in series with the anode of the first diode D ₁ , or the cathode of the first diode D ₁ must be connected in series with the cathode of the fourth voltage source V _i4 .

The fifth voltage source V _i5 and the second diode D ₂ are sequentially connected in series to form a branch, and in the same branch, the positions of the fifth voltage source V _i5 and the second diode D ₂ can be exchanged, but Depending on the direction of current flow, the anode of the fifth voltage source V _i5 must be connected in series with the anode of the second diode D ₂ , or the cathode of the second diode D ₂ must be connected in series with the cathode of the fifth voltage source V _i5 .

In addition, the transformer T can use a multi-winding transformer, and its multiple secondary windings are used as output windings to realize multiple load outputs.

When the first switching tube S ₁ and the second switching tube S ₂ are turned on, the first voltage source V _i1 , the second voltage source V _i2 , the third voltage source V _i3 and the first capacitor C ₁ are the first winding W ₁ Power supply; the second winding W ₂ charges the inductor L through the third diode D ₃ , and at the same time charges the second capacitor C ₂ to supply power to the load R. When the first switch S ₁ and the second switch S ₂ are turned off, the first diode D ₁ and the second diode D ₂ are turned on, and the third voltage source V _i3 , the fourth voltage source V _i4 , the second voltage source The five-voltage source V _i5 and the first winding W ₁ charge the first capacitor C ₁ through the first diode D ₁ and the second diode D ₂ ; the third diode D ₃ is turned off under reverse voltage, and the inductor L The _second capacitor C2 and the load R are powered by the freewheeling current through the _fourth diode D4. The utility model can realize the electrical isolation of the input side and the output side, and has larger output voltage gain.

Referring to Fig. 2a and Fig. 2b, the equivalent circuit diagrams of the two main stages in the turn-on and turn-off of the _first switching tube S1 and the _second switching tube S2 are given. Combining with Fig. 2a and Fig. 2b, the working process of the above-mentioned double-transistor forward type Z-source DC voltage converter in this embodiment is as follows:

Stage 1, as shown in Figure 2a: the first switch S ₁ and the second switch S ₂ are turned on, and at this time the first diode D ₁ , the second diode D ₂ and the fourth diode D ₄ are all subjected to The reverse voltage is cut off, and the third diode D ₃ is turned on; two loops are formed in the circuit, namely: the first voltage source V _i1 , the second voltage source V _i2 , the third voltage source V _i3 and the first capacitor C ₁ The _first winding W1 is powered by the _first switching tube S1 and the _second switching tube S2, the exciting current of the transformer exciting inductance L _m increases linearly, and the corresponding energy storage of the exciting inductance increases; the _second winding W2 passes through the third two The pole transistor _D3 charges the inductor L and at the same time charges the _second capacitor C2 to supply power to the load R.

Phase 2, as shown in Figure 2b: the _first switching tube S1 and the _second switching tube S2 are turned off, at this time, a diode D1, _{a second} diode D2 and a _fourth diode D4 are turned on, and the third The diode D ₃ is cut off under reverse pressure; two loops are formed in the circuit, namely: the third voltage source V _i3 , the fourth voltage source V _i4 , the fifth voltage source V _i5 and the first winding W ₁ through the first and second windings. The pole diode D1 and the _second diode D2 charge the _first capacitor _C1 ; the inductor L freewheels through the _fourth diode D4, and supplies power to the _second capacitor C2 and the load R at the same time.

To sum up, within one switching cycle, the switching signals of the _first switching tube S1 and the _second switching tube S2 are synchronized, and the duty cycle is d, and the excitation inductance L _m of the transformer, the inductance L and the first capacitor C The voltages of ₁ are v _Lm , v _L , and v _C1 , and the turns of the first winding and the second winding are respectively n ₁ and n ₂ , and the output voltage is V _o , the derivation process of the voltage gain is obtained as follows.

During the conduction period of the switch tube S, it corresponds to the working situation described in stage 1, so the following formula is given:

v _Lm =v _C1 +V _i1 +V _i2 +V _i3 (1)

When the switch tube S is turned off, it corresponds to the working situation described in stage 2, so the following formula is given:

v _Lm =V _i3 +V _i4 +V _i5 -v _C1 (3)

v _L ＝-V _o (4)

From the above analysis, according to the volt-second characteristics of the inductor, there are:

For the magnetizing inductance L _m :

(v _C1 +V _i1 +V _i2 +V _i3i )d+(V _i3 +V _i4 +V _i5 -v _C1 )(1-d)＝0 (5)

For inductance L:

From formula (5), the voltage expression of the first capacitor _C1 can be obtained as:

The expression of the output voltage can be obtained from the formula (6):

From the formula (8), it can be seen that the position of the power supply of the above-mentioned dual-transistor forward type Z-source DC voltage converter in this embodiment will affect the output voltage gain, wherein the voltage gain of the third power supply V _i3 is The voltage gains of the first power V _i1 , the second power V _i2 , the fourth power V _i4 and the fifth power V _i5 are all The voltage gain of the traditional two-transistor forward converter is Under the condition of the duty ratio d<0.5, the utility model can realize a larger voltage gain, and far surpasses the traditional two-tube forward converter.

In the input voltage source V _i1 =1V, V _i2 =2V, V _i3 =3V, V _i4 =4V, V _i5 =5V, the duty ratio d=0.4, and the turns ratio of the transformer is n ₁ :n ₂ =1 In the case of :4, the theoretical analysis result of the first capacitor voltage obtained from formulas (7) and (8) is v _C1 =48V, and the theoretical analysis result of the output voltage is V _o =86.4V. Referring to Figure 3, the simulation waveform under the corresponding parameters in the figure, it can be seen that the simulation result of the first capacitor voltage is also close to 48V, and the simulation result of the output voltage is also close to 86.4V, thus effectively verifying the correctness of the theoretical analysis. It can be seen that the utility model adopts the structure of the double-tube forward converter, and has the advantages of the double-tube forward converter and the Z-source converter at the same time, that is, the circuit is simple, the cost is low, the reliability is high, the driving circuit is simple, etc., and it is easy to The voltage isolation of the input and output sides is well realized, which is beneficial to the electrical insulation of the equipment, and the voltage and current ripple of the output side is small. At the same time, it can achieve a high voltage gain at a low duty cycle, and realizes multiple inputs. It is worth promoting.

The above-described embodiment is only a preferred embodiment of the utility model, not to limit the scope of implementation of the utility model, so all changes made according to the shape and principle of the utility model should be covered by the protection of the utility model within range.

Claims (3)

1. A dual-transistor forward type Z source DC voltage converter is characterized in that: said Z source DC voltage converter comprises a first voltage source (V _i1 ), a second voltage source (V _i2 ), a third voltage source source (V _i3 ), fourth voltage source (V _i4 ), fifth voltage source (V _i5 ), first capacitor (C ₁ ), second capacitor (C ₂ ), first switch tube (S ₁ ), the first Two switch tubes (S ₂ ), the first diode (D ₁ ), the second diode (D ₂ ), the third diode (D ₃ ), the fourth diode (D ₄ ), the inductor ( L), load (R) and transformer (T); the first winding (W ₁ ) of the transformer (T) is used as the primary side, and the second winding (W ₂ ) is used as the secondary side; the first capacitor (C ₁ ) are respectively connected to the drain of the first switching tube (S ₁ ) and the cathode of the second diode (D ₂ ); the negative poles of the first capacitor (C ₁ ) are respectively connected to the second switching tube (S ₂ ) is connected to the anode of the first diode (D ₁ ); the cathode of the first voltage source (V _i1 ) is connected to the source of the first switching tube (S ₁ ), and its anode is respectively connected to the third The cathode of the voltage source (V _i3 ) is connected to the anode of the fourth voltage source (V _i4 ); the cathode of the fourth voltage source (V _i4 ) is connected to the cathode of the first diode (D ₁ ); The anode of the three-voltage source (V _i3 ) is connected to the terminal of the same name of the first winding (W ₁ ); the anode of the fifth voltage source (V _i5 ) is connected to the anode of the second diode (D ₂ ), and its cathode respectively connected to the negative pole of the second voltage source (V _i2 ) and the opposite end of the first winding (W ₁ ); the same end of the second winding (W ₂ ) and the anode of the third diode (D ₃ ) connected, and its opposite end is respectively connected with the anode of the fourth diode (D ₄ ), the negative pole of the second capacitor (C ₂ ) and one end of the load (R); the third diode (D ₃ ) The cathode is respectively connected to the cathode of the fourth diode (D ₄ ) and one end of the inductance (L); the other end of the inductance (L) is respectively connected to the positive pole of the second capacitor (C ₂ ) and the other end of the load (R) One end connection; Wherein, in the case of a single input, the Z-source DC voltage converter only needs one power supply, and the other power supplies are short-circuited or the input value is zero, that is, the first power supply (V _i1 ), the second power supply (V _i2 ), the second power supply (V i2 ), and Any one of the three power supplies (V _i3 ), the fourth power supply (V _i4 ) and the fifth power supply (V _i5 ) is reserved as an input, while the other four power supplies are short-circuited or the input value is zero; similarly, in a dual-input In this case, the Z-source DC voltage converter only needs two power supplies, and the other power supplies are short-circuited or the input value is zero, that is, the first power supply (V _i1 ), the second power supply (V _i2 ), the third power supply (V _i3 ), the fourth power supply (V _i4 ) and the fifth power supply (V _i5 ) retain any two power supplies as inputs, while the other three power supplies are short-circuited or the input value is zero; similarly, in the case of three inputs, all The above-mentioned Z-source DC voltage converter only needs three power supplies, other power supplies are short-circuited or the input value is zero, that is, the first power supply (V _i1 ), the second power supply (V _i2 ), the third power supply (V _i3 ), the fourth power supply Any three power sources in the power source (V _i4 ) and the fifth power source (V _i5 ) are reserved as inputs, while the other two power sources are short-circuited or the input value is zero; similarly, in the case of four inputs, the Z source DC The voltage converter only needs four power sources, other power sources are short-circuited or the input value is zero, that is, the first power source (V _i1 ), the second power source (V _i2 ), the third power source (V _i3 ), the fourth power source (V _i4 ) and the fifth power supply (V _i5 ) retain any four power supplies as inputs, while other power supplies are short-circuited or the input value is zero; similarly, in the case of five inputs, the first of the Z-source DC voltage converter The power source (V _i1 ), the second power source (V _i2 ), the third power source (V _i3 ), the fourth power source (V _i4 ) and the fifth power source (V _i5 ) are all reserved. 2. A dual-transistor forward Z-source DC voltage converter according to claim 1, characterized in that: the first voltage source (V _i1 ) and the first switch tube (S ₁ ) are sequentially connected in series to form a branch, in the same branch, the positions of the first voltage source (V _i1 ) and the first switch tube (S ₁ ) can be exchanged, but according to the flow direction of the current, the positive electrode of the first voltage source (V _i1 ) must be connected in series The drain of the first switching tube (S ₁ ), or the source of the first switching tube (S ₁ ) is connected in series with the negative pole of the first voltage source (V _i1 ); The second voltage source (V _i2 ) and the second switch tube (S ₂ ) are sequentially connected in series to form a branch, and in the same branch, the second voltage source (V _i2 ) and the second switch tube (S ₂ ) The position can be exchanged, but according to the flow direction of the current, the anode of the second voltage source (V _i2 ) must be connected in series with the drain of the second switch (S ₂ ), or the source of the second switch (S ₂ ) should be connected in series with the second the negative pole of the voltage source (V _i2 ); The third voltage source (V _i3 ) and the first winding (W ₁ ) are sequentially connected in series to form a branch, and in the same branch, the positions of the third voltage source (V _i3 ) and the first winding (W ₁ ) It can be exchanged, but according to the flow direction of the current, the anode of the third voltage source (V _i3 ) must be connected in series with the same-named end of the first winding (W ₁ ), or the opposite-named end of the first winding (W ₁ ) should be connected in series with the third voltage source ( V _i3 ) negative pole; The fourth voltage source (V _i4 ) and the first diode (D ₁ ) are sequentially connected in series to form a branch, and in the same branch, the fourth voltage source (V _i4 ) and the first diode (D ₁ ) The position can be exchanged, but according to the current flow, the anode of the fourth voltage source (V _i4 ) must be connected in series with the anode of the first diode (D ₁ ), or the cathode of the first diode (D ₁ ) should be connected in series. the negative pole of the fourth voltage source (V _i4 ); The fifth voltage source (V _i5 ) and the second diode (D ₂ ) are sequentially connected in series to form a branch, and in the same branch, the fifth voltage source (V _i5 ) and the second diode (D ₂ ) The position can be exchanged, but according to the flow direction of the current, the anode of the fifth voltage source (V _i5 ) must be connected in series with the anode of the second diode (D ₂ ), or the cathode of the second diode (D ₂ ) must be connected in series. The negative pole of the fifth voltage source (V _i5 ). 3. a kind of two-tube forward type Z source DC voltage converter according to claim 1, is characterized in that: described transformer (T) is a multi-winding transformer, and its multiple secondary windings are used as output windings, to realize Multiple load outputs.