CN104158427B - Single-phase transless isolated form Z source photovoltaic combining inverter and modulator approach - Google Patents

Abstract

Single-phase transless isolated form Z source photovoltaic combining inverter and modulator approach, relate to photovoltaic combining inverter technical field.The present invention is to be applied in photovoltaic parallel in system to solve traditional Z-source inverter, makes grid connection efficiency low and produces the problem that common mode current is big.The present invention includes a fast recovery diode D₁, No. two fast recovery diode D₂, an electrochemical capacitor C_Z1, No. two electrochemical capacitor C_Z2, No. three electrochemical capacitor C_PV, a switching tube S₁, No. two switching tube S₂, No. three switching tube S₃, No. four switching tube S₄, No. five switching tube S₅, the 3rd inductance L_Z1With the 4th inductance L_Z2, the single-phase transless isolated form Z source photovoltaic combining inverter described in line voltage modulation all has three kinds of switching modes in positive and negative half period.It can be used in photovoltaic parallel in system.

Description

Single-phase transless isolated form Z source photovoltaic combining inverter and modulator approach

Technical field

The present invention relates to single-phase transless isolated form Z source photovoltaic combining inverter.Belong to photovoltaic combining inverter technical field.

Background technology

Z-source inverter is applied in photovoltaic parallel in system, it is possible to achieve complete boosting by the structure being similar to single stage type system simultaneously With the function of inversion two-stage system, the feature big to adapt to photovoltaic cell voltage change range.At present, domestic and international experts and scholars The application in photovoltaic parallel in system of the traditional and various modified model Z-source inverters is carried out substantial amounts of research, improves biography The service behaviour of system Z-source inverter, but their common drawback is to be required for utilizing extra transformation in actual grid-connected application Device, as the electrical isolation device between photovoltaic system and electrical network, so can make the cost of system, volume, weight and loss increase Add, make the efficiency of system reduce, so that the advantage of Z-source inverter does not perform to ultimate attainment.Rather than isolation type grid-connected inversion Device does not uses isolating transformer, and simplified system also has low cost, efficiency advantages of higher, contributes to promoting parallel network power generation The development of technology.So, research non-isolation type Z source photovoltaic combining inverter, Z-source inverter both can have been utilized more traditional inverse Become the advantage of device, the advantage of non-isolation type combining inverter can be played again to a certain extent.

Stray element influential on common mode current is there is, i.e. between photovoltaic array and ground in non-isolation type combining inverter Stray capacitance, inverter output midpoint and ground between stray capacitance, inverter and electrical network earth point between series resistance. These stray elements form common mode resonance circuit together with filter element, electric network impedance, photovoltaic array and ground in resonance circuit Between the voltage at stray capacitance two ends can change because of inverter switching device action, thus excitation common mode resonance circuit produces common mode electricity Stream.And the appearance of common mode current can increase system loss, cause Conduction Interference and radiation interference, increase grid-connected current harmonic wave, Affect Electromagnetic Compatibility and safety issue.

Traditional Z source photovoltaic combining inverter has the common-mode voltage that high frequency changes, therefore thereby produces the biggest common mode current, should Topological structure is not suitable for non-isolation type photovoltaic grid-connected inverting system.

Summary of the invention

The present invention is to be applied in photovoltaic parallel in system to solve traditional Z-source inverter, and grid connection efficiency is low and produces altogether Mould electric current is big, common-mode voltage poor stability, the problem of inverter less barrier property.Single-phase transless isolated form Z source is now provided Photovoltaic combining inverter and modulator approach.

Single-phase transless isolated form Z source photovoltaic combining inverter, it includes photovoltaic array module U_PV, the first inductance L_ac1、 Second inductance L_ac2With electrical network u_g, it also includes a fast recovery diode D₁, No. two fast recovery diode D₂, an electrolysis Electric capacity C_Z1, No. two electrochemical capacitor C_Z2, No. three electrochemical capacitor C_PV, a switching tube S₁, No. two switching tube S₂, No. three open Close pipe S₃, No. four switching tube S₄, No. five switching tube S₅, the 3rd inductance L_Z1With the 4th inductance L_Z2,

Described photovoltaic array module U_PVCathode output end be simultaneously connected with a fast recovery diode D₁Anode and No. three electrolysis Electric capacity C_PVPositive pole, a fast recovery diode D₁Negative electrode be simultaneously connected with an electrochemical capacitor C_Z1Positive pole and the 3rd electricity Sense L_Z1One end, the 3rd inductance L_Z1The other end be simultaneously connected with No. two electrochemical capacitor C_Z2Positive pole and No. five switching tube S₅'s Colelctor electrode, No. five switching tube S₅Emitter stage be simultaneously connected with a switching tube S₁Colelctor electrode and No. three switching tube S₃Current collection Pole, a switching tube S₁Emitter stage be simultaneously connected with No. two switching tube S₂Colelctor electrode and the first inductance L_ac1One end, No. three Switching tube S₃Emitter stage be simultaneously connected with No. four switching tube S₄Colelctor electrode and the second inductance L_ac2One end, the first inductance L_ac1 The other end connect electrical network u_gOne end, electrical network u_gThe other end connect the second inductance L_ac2The other end,

A number electrochemical capacitor C_Z1Negative pole be simultaneously connected with the 4th inductance L_Z2One end, No. two switching tube S₂Emitter stage and four Number switching tube S₄Emitter stage, the 4th inductance L_Z2The other end be simultaneously connected with No. two electrochemical capacitor C_Z2Negative pole and No. two fast Recovery diode D₂Anode, No. two fast recovery diode D₂Negative electrode be simultaneously connected with No. three electrochemical capacitor C_PVNegative pole and Photovoltaic array module U_PVCathode output end.

Using the modulator approach that single-phase transless isolated form Z source photovoltaic combining inverter realizes, this modulator approach is:

Single-phase transless isolated form Z source photovoltaic combining inverter described in line voltage modulation all has three in positive and negative half period Plant switching mode,

When line voltage is positive half period, controls inverter circulation and be operated in effective status, pass-through state, zero state, straight Logical state and effective status, the control signal of described effective status is S_1,2,3,4,5={ 1001 1}, the control signal of zero state is S_1,2,3,4,5={ 1010 0}, the control signal of pass-through state is S_1,2,3,4,5={ 1011 1}；

When line voltage is negative half-cycle, controls inverter circulation and be operated in effective status, pass-through state, zero state, straight Logical state and effective status, the control signal of described effective status is S_1,2,3,4,5={ 0110 1}, the control signal of zero state is S_1,2,3,4,5={ 1010 0}, the control signal of pass-through state is S_1,2,3,4,5={ 1110 1}.

The invention have the benefit that five switching tubes of the present invention all can produce in line voltage is positive and negative half period 3 kinds of switching modes, the commutation circuit of 3 kinds of switching modes has in being effective status, zero state and pass-through state and each half cycle Two switching tubes are respectively at permanent conducting or permanent off state, and on off state reduces, and the switching loss of system reduces, grid-connected effect Rate is high.When effective status and zero state, an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Charging, the 3rd inductance L_Z1 With the 4th inductance L_Z2Release energy, inductive current i_L1And i_L2Decline；

When pass-through state, an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Electric discharge, the 3rd inductance L_Z1With the 4th inductance L_Z2From an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Obtain energy, in inverter commutation course, at pass-through state Between tradition zero state and effective status, and only No. one switching tube S₁With No. three switching tube S₃The tradition zero of afterflow conducting , there are not No. two switching tube S in state₂With No. four switching tube S₄The zero state of afterflow conducting, common mode capacitance voltages keep constant； Under pass-through state, a fast recovery diode D₁, No. two fast recovery diode D₂Can blocking light photovoltaic array inverse with Z source Become device, common mode capacitance voltage discharge off path.Therefore, this inverter topology common mode current is the least.

In order to verify the practicality of the inventive method, use the New single-phase transless isolated form Z source proposed grid-connected inverse Become device topological structure, devise the experimental prototype of a rated power 1kW.Line voltage 220VAC, power frequency 50Hz, switch Frequency is 10kHz.

Accompanying drawing explanation

Fig. 1 is the principle schematic of the single-phase transless isolated form Z source photovoltaic combining inverter described in detailed description of the invention one,

Fig. 2 is the single-phase non-isolated Z-source inverter positive half period PWM strategy principle described in detailed description of the invention two Schematic diagram, reference 1 represents pass-through state, T_sRepresenting switch periods, T represents the straight-through time,

Fig. 3 is the single-phase non-isolated Z-source inverter negative half-cycle PWM strategy principle described in detailed description of the invention two Schematic diagram, reference 1 represents pass-through state,

Fig. 4 is line voltage of the present invention current direction of zero state when being positive half period,

Fig. 5 is line voltage of the present invention current direction of pass-through state when being positive half period,

Fig. 6 is line voltage of the present invention current direction of effective status when being positive half period,

Fig. 7 is line voltage of the present invention current direction of zero state when being negative half-cycle,

Fig. 8 is line voltage of the present invention current direction of pass-through state when being negative half-cycle,

Fig. 9 is line voltage of the present invention current direction of effective status when being negative half-cycle,

Figure 10 is grid-connected current of the present invention and grid voltage waveform figure, and reference 2 represents grid-connected current waveform, attached Figure labelling 3 represents grid voltage waveform,

Figure 11 is the equivalent circuit of the single-phase non-isolated Z source non-pass-through state of photovoltaic combining inverter,

Figure 12 is the equivalent circuit of single-phase non-isolated Z source photovoltaic combining inverter pass-through state.

Detailed description of the invention

Detailed description of the invention one: illustrate present embodiment with reference to Fig. 1, the single-phase transless described in present embodiment every Release Z source photovoltaic combining inverter, it includes photovoltaic array module U_PV, the first inductance L_ac1, the second inductance L_ac2And electrical network u_g, it also includes a fast recovery diode D₁, No. two fast recovery diode D₂, an electrochemical capacitor C_Z1, No. two electrolysis Electric capacity C_Z2, No. three electrochemical capacitor C_PV, a switching tube S₁, No. two switching tube S₂, No. three switching tube S₃, No. four switching tubes S₄, No. five switching tube S₅, the 3rd inductance L_Z1With the 4th inductance L_Z2,

Described photovoltaic array module U_PVCathode output end be simultaneously connected with a fast recovery diode D₁Anode and No. three electrolysis Electric capacity C_PVPositive pole, a fast recovery diode D₁Negative electrode be simultaneously connected with an electrochemical capacitor C_Z1Positive pole and the 3rd electricity Sense L_Z1One end, the 3rd inductance L_Z1The other end be simultaneously connected with No. two electrochemical capacitor C_Z2Positive pole and No. five switching tube S₅'s Colelctor electrode, No. five switching tube S₅Emitter stage be simultaneously connected with a switching tube S₁Colelctor electrode and No. three switching tube S₃Current collection Pole, a switching tube S₁Emitter stage be simultaneously connected with No. two switching tube S₂Colelctor electrode and the first inductance L_ac1One end, No. three Switching tube S₃Emitter stage be simultaneously connected with No. four switching tube S₄Colelctor electrode and the second inductance L_ac2One end, the first inductance L_ac1 The other end connect electrical network u_gOne end, electrical network u_gThe other end connect the second inductance L_ac2The other end,

A number electrochemical capacitor C_Z1Negative pole be simultaneously connected with the 4th inductance L_Z2One end, No. two switching tube S₂Emitter stage and four Number switching tube S₄Emitter stage, the 4th inductance L_Z2The other end be simultaneously connected with No. two electrochemical capacitor C_Z2Negative pole and No. two fast Recovery diode D₂Anode, No. two fast recovery diode D₂Negative electrode be simultaneously connected with No. three electrochemical capacitor C_PVNegative pole and Photovoltaic array module U_PVCathode output end.

Detailed description of the invention two: illustrate present embodiment with reference to Fig. 2 and Fig. 3, uses described in detailed description of the invention one The modulator approach that single-phase transless isolated form Z source photovoltaic combining inverter realizes, this modulator approach is:

When line voltage is positive half period, controls inverter circulation and be operated in effective status, pass-through state, zero state, straight Logical state and effective status, the control signal of described effective status is S_1,2,3,4,5={ 1001 1}, the control signal of zero state is S_1,2,3,4,5={ 1010 0}, the control signal of pass-through state is S_1,2,3,4,5={ 1011 1}；

When line voltage is negative half-cycle, controls inverter circulation and be operated in effective status, pass-through state, zero state, straight Logical state and effective status, the control signal of described effective status is S_1,2,3,4,5={ 0110 1}, the control signal of zero state is S_1,2,3,4,5={ 1010 0}, the control signal of pass-through state is S_1,2,3,4,5={ 1110 1}.

The modulator approach of present embodiment, is to be converted between effective status in zero state to increase the pass-through state of T`/2, It is transformed between zero state the pass-through state too increasing T`/2, this pass-through state at effective status, is in traditional zero shape Between state and effective status, a fast recovery diode D1 and No. two fast recovery diode D2 can blocking light photovoltaic array and Z Source inventer so that common mode capacitance voltage discharge off path, therefore so that the common mode current of inverter topology is the least.

Detailed description of the invention three: illustrate present embodiment with reference to Fig. 4, Fig. 5 and Fig. 6, present embodiment is real with concrete The difference executing the modulator approach using single-phase transless isolated form Z source photovoltaic combining inverter to realize described in mode two exists In, when line voltage is positive half period, No. three switching tube S₃On off state by modulate than for M sinusoidal reference signal with The signal that carried-based PWM produces is controlled, No. four switching tube S₄On off state with No. three switching tube S₃Complementary conducting On the basis of add straight-through time, No. five switching tube S₅On off state and No. four switching tube S₄Synchronize.

In present embodiment, modulate ratio for M in the range of 0 < M≤1.

In present embodiment, in zero state S when line voltage is positive half period_1,2,3,4,5={ 1010 0}, a described fast recovery Diode D₁, No. two fast recovery diode D₂With a switching tube S₁Conducting, No. two switching tube S₂, No. four switching tube S₄With No. five switching tube S₅Turn off, wherein, No. three diode S₃Anti-paralleled diode turns on, an electrochemical capacitor C_Z1With No. two electricity Solve electric capacity C_Z2Charging, the 3rd inductance L_Z1With the 4th inductance L_Z2Release energy, inductive current i_L1And i_L2Decline；Such as Fig. 4 Shown in,

In pass-through state S when line voltage is positive half period_1,2,3,4,5={ 1011 1}, a described switching tube S₁, No. three switches Pipe S₃, No. four switching tube S₄With No. five switching tube S₅Conducting, a fast recovery diode D₁, No. two fast recovery diode D₂ With No. two switching tube S₂Turn off, wherein, No. three switching tube S₃Anti-paralleled diode turns on, an electrochemical capacitor C_Z1With No. two Electrochemical capacitor C_Z2Electric discharge, the 3rd inductance L_Z1With the 4th inductance L_Z2From an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2 Obtain energy, as it is shown in figure 5,

At effective status S when line voltage is positive half period_1,2,3,4,5={ 1001 1}, a described fast recovery diode D₁, two Number fast recovery diode D₂, a switching tube S₁, No. four switching tube S₄With No. five switching tube S₅Conducting, No. two switching tube S₂ With No. three switching tube S₃Turn off, an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Charging, the 3rd inductance L_Z1With the 4th electricity Sense L_Z2Release energy, inductive current i_L1And i_L2Decline；As shown in Figure 6.

Detailed description of the invention four: illustrate present embodiment with reference to Fig. 7, Fig. 8 and Fig. 9, present embodiment is real with concrete The difference executing the modulator approach using single-phase transless isolated form Z source photovoltaic combining inverter to realize described in mode two exists In, when line voltage is negative half-cycle, a switching tube S₁On off state by modulate than for M sinusoidal reference signal with The signal that carried-based PWM produces is controlled, No. two switching tube S₂On off state with a switching tube S₁Complementary conducting On the basis of add straight-through time, No. five switching tube S₅On off state and No. two switching tube S₂Synchronize.

In zero state S when line voltage is negative half-cycle_1,2,3,4,5={ 1010 0}, a described fast recovery diode D₁, No. two Fast recovery diode D₂With No. three switching tube S₃Conducting, No. two switching tube S₂, No. four switching tube S₄With No. five switching tube S₅Close Disconnected, wherein, a switching tube S₁Antiparallel diode current flow, an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Fill Electricity, the 3rd inductance L_Z1With the 4th inductance L_Z2Release energy, inductive current i_L1And i_L2Decline；As it is shown in fig. 7,

In pass-through state S when line voltage is negative half-cycle_1,2,3,4,5={ 1110 1}, a described switching tube S₁, No. two switches Pipe S₂, No. three switching tube S₃With No. five switching tube S₅Conducting, a fast recovery diode D₁, No. two fast recovery diode D₂ With No. four switching tube S₄Turn off, wherein, a diode S₁Antiparallel diode current flow, an electrochemical capacitor C_Z1With two Number electrochemical capacitor C_Z2Electric discharge, the 3rd inductance L_Z1With the 4th inductance L_Z2From an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2 Acquisition energy, as shown in Figure 8,

At effective status S when line voltage is negative half-cycle_1,2,3,4,5={ 0110 1}, a described fast recovery diode D₁, two Number fast recovery diode D₂, No. two switching tube S₂, No. three switching tube S₃With No. five switching tube S₅Conducting, a switching tube S₁ With No. four switching tube S₄Turn off, an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Charging, the 3rd inductance L_Z1With the 4th electricity Sense L_Z2Release energy, inductive current i_L1And i_L2Decline；As shown in Figure 9.

In the present invention, single-phase transless isolated form Z source photovoltaic combining inverter is modulated by line voltage, at electrical network electricity All having three kinds of switching modes in positive pressure negative half-cycle, when pass-through state, Z source electric capacity discharges, and Z source inductance is from Z source electric capacity Obtain energy.A number fast recovery diode D₁, No. two fast recovery diode D₂Can blocking light photovoltaic array and Z-source inverter, Common mode capacitance voltage discharge off path.

Figure 10 is grid-connected current and grid voltage waveform, and both frequencies are equal, phase place is basically identical, meets grid-connected requirement.Institute The common-mode voltage waveform produced shows, when effective status and zero state, common-mode voltage remains constant.

In the present invention, the principle Analysis method of single-phase non-isolated Z-source inverter is similar with traditional Z source inventer, first Assume that Z source network is symmetrical network, then an electrochemical capacitor C_Z1, No. two electrochemical capacitor C_Z2With the 3rd inductance L_Z1With the 4th inductance L_Z2Meet:

$\left\{\begin{array}{c}{L}_{Z1}=L_{Z2}=L\\ C_{Z1}=C_{Z2}=C\end{array}\right.---\left(1\right)$

According to symmetrical and the principle of equal effects, have

$\left\{\begin{array}{c}{U}_{L1}=U_{L2}=U_L\\ U_{C1}=U_{C2}=U_C\end{array}\right.---\left(2\right)$

According to switch periods T_SWhether interior inverter bridge is operated in direct mode operation, single-phase non-isolated Z-source inverter and tradition Z-source inverter is the same, there is also two kinds of duties: pass-through state and non-pass-through state.Under pass-through state, Z source energy storage net Carrying out energy exchange between network internal inductance electric capacity, it is to avoid the instantaneous variation of voltage or electric current, this opens at effectively protection power Also provide the buck characteristic of uniqueness for inverter while closing device.

(1) non-pass-through state is according to non-straight-through status circuit equivalence Figure 11), a now fast recovery diode D₁, two Number fast recovery diode D₂Forward conduction, Z source network energy storage inductor passes through load discharge, and inverter bridge can be equivalent to a controlled electricity Stream source i_i.Assume switch periods T_SIn, it is T that inverter bridge is operated in the time of non-pass-through state₁, have

$\left\{\begin{array}{c}{U}_{FB}=U_C-U_L=2U_C-U_{PV}\\ U_d=U_{PV}=U_L+U_C\end{array}\right.---\left(3\right)$

Wherein, U_PVFor photovoltaic array module；U_dIt is a fast recovery diode D₁Negative electrode and No. two fast recovery diode D₂Anode Between voltage；U_FBFor inverter bridge busbar voltage.

(2) pass-through state is according to pass-through state circuit equivalent Figure 12), now diode D₁And D₂Bear back-pressure and close Disconnected, inverter bridge short circuit.Switch periods T_SIn, inverter bridge pass-through state working time and non-straight-through operation time Complementation, if the working time of pass-through state is T (T=T_S-T₁), have

$\left\{\begin{array}{c}{U}_L=U_C\\ U_{FB}=0\\ U_d=2U_C>U_{PV}\end{array}\right.---\left(4\right)$

Under steady-state conditions, from the voltage-second balance principle of DC inductance, in a switch periods, energy storage inductor two ends, Z source Average voltage be necessarily zero, by formula (3) and formula (4)

U_CT+(U_PV-U_C)T₁=0 (5)

Arrange Z source capacitance voltage is

$U_C=\frac{T_1}{T_1-T}{U}_{PV}---\left(6\right)$

In like manner understanding, inverter bridge DC side average voltage is

$U_{FB}=\frac{T_1}{T_1-T}{U}_{PV}=U_C---\left(7\right)$

Under non-pass-through state, the gain B of input voltage is by inverter bridge bus crest voltage

$B=\frac{{\hat{U}}_{FB}}{U_{PV}}=\frac{T_S}{T_1-T}=\frac{1}{1-2d_0}\&GreaterEqual;1---\left(8\right)$

Wherein,For inverter bridge bus crest voltage；d₀For straight-through dutycycle, d₀=T '/T_S。

The Sine Modulated factor M of inverter is

$M=\frac{{\hat{u}}_{ab}}{{\hat{U}}_{FB}}\&le;1---\left(9\right)$

Wherein,For exchange output sinusoidal voltage first-harmonic peak value.

Therefore, whole single-phase non-isolated Z-source inverter output voltage is

${\hat{u}}_{ab}={\hat{U}}_{FB}M=\frac{T_S}{T_1-T}{U}_{PV}M={\mathrm{BMU}}_{PV}---\left(10\right)$

From formula (10), when non-isolation type Z-source inverter is applied to photovoltaic parallel in system, its AC voltage is by electrical network institute Clamp down on, therefore the grid-connected of the DC side input voltage of arbitrary size can be realized by the straight-through dutycycle of modulation and the Sine Modulated factor. Compared to conventional voltage source type inverter, single-phase non-isolated Z-source inverter is before need not extra intergrade translation circuit Put, expand the transformation range of system, improve the combination property of system.

Claims (2)

1. The most single-phase transless isolated form Z source photovoltaic combining inverter, it includes photovoltaic array module U_PV, the first inductance L_ac1、 Second inductance L_ac2With electrical network u_g, it is characterised in that it also includes a fast recovery diode D₁, No. two fast recovery diodes D₂, an electrochemical capacitor C_Z1, No. two electrochemical capacitor C_Z2, No. three electrochemical capacitor C_PV, a switching tube S₁, No. two switches Pipe S₂, No. three switching tube S₃, No. four switching tube S₄, No. five switching tube S₅, the 3rd inductance L_Z1With the 4th inductance L_Z2,

   Described photovoltaic array module U_PVCathode output end be simultaneously connected with a fast recovery diode D₁Anode and No. three electrolysis Electric capacity C_PVPositive pole, a fast recovery diode D₁Negative electrode be simultaneously connected with an electrochemical capacitor C_Z1Positive pole and the 3rd electricity Sense L_Z1One end, the 3rd inductance L_Z1The other end be simultaneously connected with No. two electrochemical capacitor C_Z2Positive pole and No. five switching tube S₅'s Colelctor electrode, No. five switching tube S₅Emitter stage be simultaneously connected with a switching tube S₁Colelctor electrode and No. three switching tube S₃Current collection Pole, a switching tube S₁Emitter stage be simultaneously connected with No. two switching tube S₂Colelctor electrode and the first inductance L_ac1One end, No. three Switching tube S₃Emitter stage be simultaneously connected with No. four switching tube S₄Colelctor electrode and the second inductance L_ac2One end, the first inductance L_ac1 The other end connect electrical network u_gOne end, electrical network u_gThe other end connect the second inductance L_ac2The other end,

   A number electrochemical capacitor C_Z1Negative pole be simultaneously connected with the 4th inductance L_Z2One end, No. two switching tube S₂Emitter stage and four Number switching tube S₄Emitter stage, the 4th inductance L_Z2The other end be simultaneously connected with No. two electrochemical capacitor C_Z2Negative pole and No. two fast Recovery diode D₂Anode, No. two fast recovery diode D₂Negative electrode be simultaneously connected with No. three electrochemical capacitor C_PVNegative pole and Photovoltaic array module U_PVCathode output end；

   When line voltage is positive half period, No. three switching tube S₃On off state by modulate than for M sinusoidal reference signal with The signal that carried-based PWM produces is controlled, No. four switching tube S₄On off state with No. three switching tube S₃Complementary conducting On the basis of add straight-through time, No. five switching tube S₅On off state and No. four switching tube S₄Synchronize；

   When line voltage is negative half-cycle, a switching tube S₁On off state by modulate than for M sinusoidal reference signal with The signal that carried-based PWM produces is controlled, No. two switching tube S₂On off state with a switching tube S₁Complementary conducting On the basis of add straight-through time, No. five switching tube S₅On off state and No. two switching tube S₂Synchronize；

   Pass-through state, a fast recovery diode D1 and No. two fast recovery diode D2 can blocking light photovoltaic array inverse with Z source Become device so that common mode capacitance voltage discharge off path, therefore so that the common mode current of inverter topology is the least,

   In zero state S when line voltage is positive half period_1,2,3,4,5={ 1010 0}, a described fast recovery diode D₁, No. two Fast recovery diode D₂With a switching tube S₁Conducting, No. two switching tube S₂, No. four switching tube S₄With No. five switching tube S₅Close Disconnected, wherein, No. three diode S₃Anti-paralleled diode turns on, an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Charging, 3rd inductance L_Z1With the 4th inductance L_Z2Release energy, inductive current i_L1And i_L2Decline；

   In pass-through state S when line voltage is positive half period_1,2,3,4,5={ 1011 1}, a described switching tube S₁, No. three switches Pipe S₃, No. four switching tube S₄With No. five switching tube S₅Conducting, a fast recovery diode D₁, No. two fast recovery diode D₂ With No. two switching tube S₂Turn off, wherein, No. three switching tube S₃Anti-paralleled diode turns on, an electrochemical capacitor C_Z1With No. two Electrochemical capacitor C_Z2Electric discharge, the 3rd inductance L_Z1With the 4th inductance L_Z2From an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2 Obtain energy；

   At effective status S when line voltage is positive half period_1,2,3,4,5={ 1001 1}, a described fast recovery diode D₁, two Number fast recovery diode D₂, a switching tube S₁, No. four switching tube S₄With No. five switching tube S₅Conducting, No. two switching tube S₂ With No. three switching tube S₃Turn off, an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Charging, the 3rd inductance L_Z1With the 4th electricity Sense L_Z2Release energy, inductive current i_L1And i_L2Decline；

   In zero state S when line voltage is negative half-cycle_1,2,3,4,5={ 1010 0}, a described fast recovery diode D₁, No. two Fast recovery diode D₂With No. three switching tube S₃Conducting, No. two switching tube S₂, No. four switching tube S₄With No. five switching tube S₅Close Disconnected, wherein, a switching tube S₁Antiparallel diode current flow, an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Fill Electricity, the 3rd inductance L_Z1With the 4th inductance L_Z2Release energy, inductive current i_L1And i_L2Decline；

   In pass-through state S when line voltage is negative half-cycle_1,2,3,4,5={ 1110 1}, a described switching tube S₁, No. two switches Pipe S₂, No. three switching tube S₃With No. five switching tube S₅Conducting, a fast recovery diode D₁, No. two fast recovery diode D₂ With No. four switching tube S₄Turn off, wherein, a diode S₁Antiparallel diode current flow, an electrochemical capacitor C_Z1With two Number electrochemical capacitor C_Z2Electric discharge, the 3rd inductance L_Z1With the 4th inductance L_Z2From an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2 Obtain energy；

   At effective status S when line voltage is negative half-cycle_1,2,3,4,5={ 0110 1}, a described fast recovery diode D₁, two Number fast recovery diode D₂, No. two switching tube S₂, No. three switching tube S₃With No. five switching tube S₅Conducting, a switching tube S₁ With No. four switching tube S₄Turn off, an electrochemical capacitor C_Z1With No. two electrochemical capacitor C_Z2Charging, the 3rd inductance L_Z1With the 4th electricity Sense L_Z2Release energy, inductive current i_L1And i_L2Decline.
2. 2. use the modulator approach that the single-phase transless isolated form Z source photovoltaic combining inverter described in claim 1 realizes, It is characterized in that, this modulator approach is:

   Single-phase transless isolated form Z source photovoltaic combining inverter described in line voltage modulation all has three in positive and negative half period Plant switching mode,

   When line voltage is positive half period, controls inverter circulation and be operated in effective status, pass-through state, zero state, straight Logical state and effective status, the control signal of described effective status is S_1,2,3,4,5={ 1001 1}, the control signal of zero state is S_1,2,3,4,5={ 1010 0}, the control signal of pass-through state is S_1,2,3,4,5={ 1011 1}；

   When line voltage is negative half-cycle, controls inverter circulation and be operated in effective status, pass-through state, zero state, straight Logical state and effective status, the control signal of described effective status is S_1,2,3,4,5={ 0110 1}, the control signal of zero state is S_1,2,3,4,5={ 1010 0}, the control signal of pass-through state is S_1,2,3,4,5={ 1110 1}.