CN105099250A - Capacitor-free Z-source inverter topological structure - Google Patents

Abstract

In a capacitor-free Z-source inverter topological structure, an inductance type Z-source network is connected between a direct current power supply and an inverter bridge, and the Z-source network is formed by two parts connected in parallel, i.e., a switching tube unit formed by a switching rube with an antiparallel diode and a single inductor which connected in series, and an expansion switch inductance network formed by an inductor and a diode; the expansion switch inductance network includes n-1 circuit units formed by n inductors, each circuit unit includes two inductors and three diodes, the two inductors are a 1# inductor and a 2# inductor, and the three diodes are a 1# diode, a 2# diode and a 3# diode; and for two adjacent units, the 2# inductor of the previous unit is the 1# inductor of the next unit. The structure can prolong the service life of a system, reduce the volume of the system and reduce system cost, avoids a resonance phenomenon caused by coexistence of capacitors and inductors, avoids impact current existing in starting of the Z-source inverter, and allows existence of a zero state.

Description

Without electric capacity Z-source inverter topological structure

Technical field

The present invention relates to a kind of inverter, particularly a kind of without electric capacity Z-source inverter topological structure.

Background technology

The topological structure of existing Z-source inverter has multiple, as: traditional Z source inventer as shown in Figure 2, accurate Z-source inverter as shown in Figure 3, switched inductors Z-source inverter as shown in Figure 4 and accurate switched inductors Z-source inverter etc. as shown in Figure 5.As can be seen from Fig. 2 ~ 5, in above various Z-source inverter except having inductance element, all containing capacity cell.Due to the existence of capacity cell, then inevitably exist lifetime of system shorter, may exist between inductance and electric capacity resonance phenomena, system start time may there is impulse current; In addition, in above Z-source inverter, inductive current stress is comparatively large, and can only change voltage gain by the mode changing straight-through duty ratio.

In addition, not containing capacity cell in inductance-type Z-source inverter, only containing inductance and diode element, but this inverter belongs to current source inverter, only containing straight-through and active switch state, not containing zero switching state.

Summary of the invention

For above problem, the object of this invention is to provide a kind of without electric capacity Z-source inverter topological structure, this structure can extend useful life of system, reduction system volume, reduce system cost, avoid because electric capacity and inductance coexist the resonance phenomena caused, avoid the impulse current existed when Z-source inverter starts, and allow the existence of nought state.

As above conceive, technical scheme of the present invention is: a kind of without electric capacity Z-source inverter topological structure, comprise DC power supply and inverter bridge, it is characterized in that: between DC power supply with inverter bridge, be connected an inductive type Z source network, this inductive type Z source network is composed in parallel by two parts, and they are: the expansion switch inductance network that the switching tube unit, inductance and the diode that are composed in series by switching tube and the single inductance of band anti-paralleled diode form; N-1 the circuit unit that described expansion switch inductance network is made up of n inductance, each circuit unit contains two inductance and three diodes, two inductance are respectively 1# inductance and 2# inductance, and three diodes are respectively 1# diode, 2# diode and 3# diode; For two adjacent cells, the 2# inductance of previous element is the 1# inductance of a rear unit; One end of the 1# inductance of described each circuit unit is connected with the anode of 1# diode, and the other end of 1# inductance is connected with the anode of 2# with 3# diode; One end of 2# inductance is connected with the negative electrode of 1# with 2# diode, and the other end of 2# inductance is connected with the negative electrode of 3# diode.

Described inductive type Z source network is connected between DC power supply and the lower brachium pontis of inverter bridge.

Described inductive type Z source network is connected between DC power supply and the upper brachium pontis of inverter bridge.

The course of work of the present invention is:

1, when working in pass-through state, any one unit in described diode and inductance network, 1# and 3# diode current flow, 2# diode ends, 1# and the 2# inductance in each unit in being connected in parallel, now inductance stored energy; 0# diode current flow, 0# inductance stored energy.

2, when working in non-pass-through state, any one unit in described expansion switch inductance network, 1# and 3# diode ends, 2# diode current flow, 1# and the 2# inductance in each unit is in being connected in series, and now inductance releases energy to load; 0# diode current flow, 0# inductance releases energy.

3, when inverter works in nought state, the switching tube S7 conducting in switching tube unit, for the inductance in expansion switch inductance network provides continuous current circuit, avoids the voltage pump rise that discontinuous current mode produces, and then the uncontrollable problem of the system caused.

The present invention has following advantage and good effect:

1. solve the defect that can not contain nought state in inductance-type Z-source inverter.

2. remove capacity cell as part necessary in Z source network in Z-source inverter, the useful life of system, reduction system volume can be extended and reduce system cost.

3., owing to eliminating capacity cell, the inductance-type Z-source inverter of improvement avoids because electric capacity and inductance coexist the resonance phenomena caused.

4., owing to eliminating capacity cell, the inductance-type Z-source inverter of improvement avoids the impulse current existed when Z-source inverter starts.

5., under the condition of identical voltage gain, the inductive current gain of the inductance-type Z-source inverter of improvement is less than traditional Z source inventer and switched inductors Z-source inverter.

Accompanying drawing explanation

Fig. 1 is of the present invention without electric capacity Z-source inverter topological structure;

Fig. 2 is traditional Z source inventer;

Fig. 3 is as the criterion Z-source inverter;

Fig. 4 is switched inductors Z-source inverter;

Fig. 5 is the accurate Z-source inverter of switched inductors;

When Fig. 6 is pass-through state of the present invention, without electric capacity Z-source inverter topological structure;

When Fig. 7 is non-pass-through state of the present invention, the inductive type Z inverter topology of improvement;

When Fig. 8 is different n value of the present invention, the inductance-type Z-source inverter voltage gain curve of improvement;

Fig. 9 is the inductance-type Z-source inverter voltage gain correlation curve that the present invention and dissimilar Z-source inverter and n improve when getting different value;

Figure 10 is the inductive current stress curve in the present invention;

Figure 11 is inductive current stress curve in switched inductors Z-source inverter and the accurate Z-source inverter of switched inductors.

Embodiment

Be illustrated without electric capacity Z-source inverter topological structure of the present invention by reference to the accompanying drawings.

As shown in Figure 1, wherein: L ₀=L ₁=L ₂l ₃=... L _n-1=L _n=L, n are the number of inductance.

The structure of the inductance-type Z-source inverter that the present invention improves is by DC power supply V _dc, inductive type Z source network and inverter bridge composition.Described inductive type Z source network is connected between DC power supply and the lower brachium pontis of inverter bridge, or is connected between DC power supply and the upper brachium pontis of inverter bridge.

Wherein inductive type Z source network is composed in parallel by two parts, and two parts are respectively: 1. by the switching tube S of band anti-paralleled diode ₇with single inductance L ₀the expansion switch inductance network of the switching tube unit, the 2. inductance that are composed in series and diode composition.Expansion switch inductance network is made up of n inductance and 3 × (n-1) individual diode.Wherein L ₁one end and D _1,1anode be connected, L ₁the other end and D _1,2and D _1,3anode be connected.L ₂one end and D _1,1and D _1,2negative electrode be connected, with D _2,1anode be connected; L ₂the other end and D _2,2and D _2,3anode be connected.By that analogy, known L _n-1one end and D _n-2,1and D _n-2,2negative electrode be connected, with D _n-1,1anode be connected; L ₂the other end and D _n-1,2and D _n-1,3anode be connected.L _none end and D _n-1,1and D _n-1,2negative electrode be connected, L _nthe other end and D _n-1,3be connected.In addition, improve inductive type Z source network and can be placed on DC power supply V _dcand between the lower brachium pontis of inverter bridge, also can be placed on DC power supply V _dcand between the upper brachium pontis of inverter bridge.

As shown in Figure 6, the equivalence of expansion switch inductance network becomes n+1 inductance in parallel, now inductance stored energy to equivalent electric circuit when working in pass-through state.

When working in non-pass-through state, equivalent electric circuit as shown in Figure 7, and equivalence can become the series connection of each inductance, now inductance releases energy to load.

The voltage gain of this Z-source inverter is:

$B=\frac{1+(n-1)D}{1-D}$

Wherein: n is the quantity of inductance in inductance and diode network; D is straight-through duty ratio.

In expansion switch inductance network, average inductor current is:

$I_{L\mathrm{1,2,3},...,n}=-\frac{D(\mathrm{nL}+L_l)+L(1-D)}{R_{l}L(1-D)}{V}_{\mathrm{dc}}$

In switching tube unit, average inductor current is:

$I_{L0}=\frac{\mathrm{nL}+(n+1){\mathrm{DL}}_l}{(n+1)(1-D)R_{l}L}{V}_{\mathrm{dc}}$

Wherein: L is the inductance value of inductance element in inductance and diode network; L _lfor load inductance; R ₁for load resistance; V _dcfor direct current power source voltage.

And each inductive current is all equal in inductance and diode network, in this Z-source inverter, load average electric current is:

$I_l=\frac{L_l(1-D)}{R_{l}D(\mathrm{nL}+L_l)+R_l{L}_l(1-D)}{V}_{\mathrm{dc}}$

When load is purely resistive, inductive current stress and load average electric current are respectively:

$I_{L0}=\frac{n}{R_l(n+1)(1-D)}{V}_{\mathrm{dc}}$

$I_{L\mathrm{1,2,3},...,n}=\frac{1+(n-1)+D}{R_l(1-D)}{V}_{\mathrm{dc}}$

$I_l=\frac{1+(n-1)D}{R_l}{V}_{\mathrm{dc}}$

The inductance-type Z-source inverter voltage gain curve of the improvement when n shown in Fig. 8 gets different value, known in figure, this inverter adjusts the voltage gain of inverter by the number containing inductance in adjustment Z source network and straight-through duty ratio two kinds of modes; Compared with other type Z-source inverter, the mode of this inverter regulation voltage gain is more diversified.

The inductance-type Z-source inverter voltage gain correlation curve that dissimilar Z-source inverter shown in Fig. 9 and n improve when getting different value.The inductance-type Z-source inverter improved as we know from the figure carrys out regulation voltage gain by the quantity adjusting inductance, can make this gain in certain interval, be better than the Z-source inverter of other type, is suitable for the situation when straight-through change in duty cycle scope is less; In addition, comparatively the change of other type Z-source inverter is steady for the voltage gain of the inductance-type Z-source inverter of improvement, makes it control so more convenient.Wherein: SL-ZSI is switched inductors type Z-source inverter; SL-qZSI is the accurate Z-source inverter of switched inductors.

During Fig. 9 difference n value, the inductance-type Z-source inverter improved and other Z-source inverter voltage gain correlation curve, inductive current stress changing curve in the inductance-type Z-source inverter that Figure 10 improves, Figure 11 is inductive current stress correlation curve in switched inductors type Z-source inverter and the accurate Z-source inverter of switched inductors.

As can be seen from Figure 10 and 11, in the inductance-type Z-source inverter improved, inductive current STRESS VARIATION is less of n=2,4,6,8, and when identical voltage gain, the inductive current stress in the inductance-type Z-source inverter of improvement is lower than the current stress in switched inductors type Z-source inverter and the accurate Z-source inverter of switched inductors.

Table 1 gives under identical straight-through duty cycle condition, the contrast (load is purely resistive) of various stress in the inductance-type Z-source inverter of improvement, inductance-type Z-source inverter, switched inductors Z-source inverter and the accurate Z-source inverter of switched inductors.

Table 1 improve inductance-type Z-source inverter and other type Z-source inverter in each element stress ratio comparatively

Claims (3)

1. one kind without electric capacity Z-source inverter topological structure, comprise DC power supply and inverter bridge, it is characterized in that: between DC power supply with inverter bridge, be connected an inductive type Z source network, this inductive type Z source network is composed in parallel by two parts, and they are: the expansion switch inductance network that the switching tube unit, inductance and the diode that are composed in series by switching tube and the single inductance of band anti-paralleled diode form; Described expansion switch inductance network is n-1 the circuit unit be made up of n inductance, each circuit unit contains two inductance and three diodes, two inductance are respectively 1# inductance and 2# inductance, and three diodes are respectively 1# diode, 2# diode and 3# diode; For two adjacent cells, the 2# inductance of previous element is the 1# inductance of a rear unit; One end of the 1# inductance of described each circuit unit is connected with the anode of 1# diode, and the other end of 1# inductance is connected with the anode of 2# with 3# diode; One end of 2# inductance is connected with the negative electrode of 1# with 2# diode, and the other end of 2# inductance is connected with the negative electrode of 3# diode.

2. according to claim 1 without electric capacity Z-source inverter topological structure, it is characterized in that: described inductive type Z source network is connected between DC power supply and the lower brachium pontis of inverter bridge.

3. according to claim 1 without electric capacity Z-source inverter topological structure, it is characterized in that: described inductive type Z source network is connected between DC power supply and the upper brachium pontis of inverter bridge.