CN204304777U - Based on the photovoltaic DC-to-AC converter of Interleaved control high-gain Boost - Google Patents

Abstract

The utility model discloses a photovoltaic inverter based on an interleaved control high-gain Boost converter. The device includes a photovoltaic array, an interleaved control high-gain Boost converter, a DC side energy storage capacitor, a full-bridge inverter, and an LCL filter. . Among them, the photovoltaic array, interleaved control high-gain Boost converter, DC side energy storage capacitor, full-bridge inverter, and LCL filter are connected in sequence and connected to the power grid through a circuit breaker. The interleaved control high-gain Boost converter is composed of two parallel boost circuits in an interleaved structure, and the inductors in the two boost circuits are coupled inductors. The utility model has the following advantages: the Boost converter and the full-bridge inverter do not need to be isolated, and the circuit topology, control and drive are simple; the switching tube and diode of the Boost converter can realize soft switching, and the switching loss is small; the Boost converter has high gain characteristics, to avoid extreme duty cycle; low harmonic content of grid-connected current.

Description

Photovoltaic Inverter Based on Interleaved Control High Gain Boost Converter

technical field

The utility model relates to the field of solar photovoltaic power generation, in particular to an LCL type non-isolated photovoltaic inverter device based on an interleaved control high-gain Boost converter.

Background technique

In recent years, the fossil energy crisis and the intensification of global environmental pollution have made photovoltaic power generation one of the research hotspots. More and more distributed photovoltaic power generation is connected to the low-voltage distribution network through inverters. However, the output DC voltage of photovoltaic arrays is lower than The input DC voltage of the grid-connected inverter, and the high-efficiency and high-gain DC/DC converter are indispensable in the solar power generation system.

The traditional Boost converter can achieve arbitrary high-gain conversion and grid-connected maximum power tracking, but it has the following bottlenecks: the voltage gain is limited by the parasitic parameters of capacitors, inductors, and switching devices, and as the duty cycle increases, the device The current and input current ripple stress increase accordingly, the switching loss increases, and the diode reverse recovery loss becomes more prominent, resulting in a decrease in converter efficiency and more serious electromagnetic interference problems. In order to develop a high-efficiency, high-gain Boost converter, corresponding research has been carried out at home and abroad, such as: using Boost converter cascading to increase conversion gain, and realizing high boost conversion of isolated Boost converter through reasonable design of transformer ratio; A combination of Boost converter and Flyback converter is used to realize high-gain conversion. However, the topological structure of the high-gain Boost converter studied at present is complex, the stress current of the device is large, the input current ripple is large, and the limit duty cycle appears in high-gain applications, which is not suitable for high-power applications.

The utility model proposes a photovoltaic inverter based on an interleaved control high-gain Boost converter. High-gain conversion can be realized by rationally designing the parameters of the improved Boost converter. All switches and diodes can be turned off and turned on with zero current or zero voltage without adding any auxiliary circuit, and the topology of the main circuit is relatively simple. The input current ripple is small, which reduces the conduction loss, reduces the volume of the input filter circuit, and improves the power density; the LCL filter is used in the grid-connected system to reduce the total inductance and meet the requirements of low distortion rate grid-connected.

Contents of the invention

The technical problem to be solved by the utility model is to provide a photovoltaic inverter based on an interleaved control high-gain Boost converter in view of the deficiencies in the prior art, rationally design the coupling coefficient of the coupling inductor in the two parallel Boost circuits, and realize high gain The switch and diode have soft switching characteristics, and the conduction loss is low; the input current of the improved Boost converter is the sum of the two-phase current, the ripple frequency is twice the switching frequency, and the peak-to-peak value of the ripple Small size, the input filter is small; LCL filter is used to reduce the total inductance and realize low distortion rate grid connection.

In order to solve the above problems, the technical solution of this utility model is: a photovoltaic inverter based on interleaved control high-gain Boost converter, including photovoltaic array, interleaved control high-gain Boost converter, DC side energy storage capacitor, full-bridge inverter Transformer, LCL filter. The photovoltaic array, the interleaved control high-gain Boost converter, the DC side energy storage capacitor, the full-bridge inverter, and the LCL filter are connected in sequence, and connected to the power grid through a circuit breaker; the interleaved control high-gain Boost converter consists of two parallel Boost The voltage circuits are combined in an interleaved manner, and the inductors in the two traditional Boost circuits are coupled inductors.

Reasonably design the coupling coefficient of the coupling inductor in the two parallel Boost circuits to realize high-gain conversion and avoid the limit duty cycle.

The interleaved control high-gain Boost converter has the characteristic of zero current transfer.

The coupling-inductance coupling coefficient of the interleaved control high-gain Boost converter is 0.91.

The input current of the interleaved control high-gain Boost converter is the sum of the two-phase currents, and the input current ripple is small.

Compared with the prior art, the utility model has the following advantages: the Boost converter and the full-bridge inverter do not need to be isolated, the circuit topology, control and drive are simple, and the device is small in size; the switching tube and diode of the Boost converter can realize soft switching , the switching loss is small; the Boost converter has high gain characteristics, avoiding the limit duty cycle; the harmonic content of the grid-connected current is low.

Description of drawings

Figure 1 is a topological structure diagram of a photovoltaic inverter based on an interleaved control high-gain Boost converter;

Fig. 2 is the equivalent circuit diagram of the working mode 1 of interleaved control high-gain Boost switch;

Fig. 3 is the equivalent circuit diagram of the working mode 2 of the interleaved control high-gain Boost converter;

Fig. 4 is the equivalent circuit diagram of the working mode 3 of the interleaved control high-gain Boost converter;

Fig. 5 is an equivalent circuit diagram of working mode 4 of the interleaved control high-gain Boost converter.

Among them: u _g - grid voltage; C _pv - photovoltaic side energy storage capacitor; L ₁ , L ₂ -Boost boost inductor; C ₁ , C ₂ - DC side voltage divider energy storage capacitor; S ₅ , S ₆ -Boost boost voltage circuit switch tube; S ₁ -S ₄ -single-phase full-bridge inverter switch tube; D _b1 and D _b2 are diodes of interleaved circuit; C _b1 and C _b2 are filter capacitors of interleaved circuit; D ₁ and D ₂ is the diode of the Boost boost circuit; i _pv - the DC current of the photovoltaic side; i _L1 , i _L2 - the DC current of the two branches of the Boost boost circuit; i _o - the DC side DC current; L ₁ , L ₂ , C-LCL Filter inductance and capacitance parameters; k is the coupling coefficient; u _dc - DC voltage measurement; K ₁ - grid-connected switch.

Detailed ways

As shown in FIG. 1 , an embodiment of the present invention includes a photovoltaic array, an interleaved control high-gain Boost converter, a DC side energy storage capacitor, a full-bridge inverter, and an LCL filter. Among them, the photovoltaic array, the interleaved control high-gain Boost converter, the DC side energy storage capacitor, the full bridge inverter, and the LCL filter are connected in sequence, connected to the power grid through the circuit breaker K ₁ , and the DC side energy storage capacitor is two 400V level The voltage dividing electrolytic capacitors C ₁ and C ₂ are connected in series. The switching tube _S0 of the single-phase full-bridge inverter _S1 - _S4 is composed of an IPM module, and the model of the IPM module is PM50B5LA060; the switching tubes _S5 and _S6 of the interleaved control high-gain Boost converter are composed of IGBT modules , the model of the IGBT module is FF450R17ME3.

The working voltage on the DC side is stable at 420V, which is obtained by controlling the switching tube of the full-bridge inverter at the rear stage. The Boost circuit realizes the maximum power tracking of the photovoltaic array, and the LCL filter realizes the attenuation of the grid-connected harmonic current. The single-phase full-bridge inverter is an existing topology, and the working mode is not described. The working mode of the interleaved control high-gain Boost converter is specifically explained.

Due to the symmetry of the circuit structure of the interleaved control high-gain Boost converter, the working conditions of the latter 1/2 cycle are similar to those of the first 1/2 cycle. Only by analyzing its working conditions in the 1/2 switching cycle can the interleaved control high There are 4 switching modes in total for the working mode of the gain Boost converter. The working conditions of each switch mode are analyzed as follows:

1) Fig. 2 shows the equivalent circuit diagram of the working mode 1 of the interleaved control high-gain Boost converter. Before time t _a , switches S ₅ and S ₆ are turned on, diodes D _b1 , D _b2 , D ₁ , and D ₂ are turned off, the capacitor voltage u _b1 is zero, and the capacitor voltage u _b2 is the output voltage u _dc . At time t _a , S ₂ is turned off, diodes D _b2 and D ₂ are turned on, capacitor C _b1 is charged through the loop of "photovoltaic array-C _pv -L ₂ -D _b2 -S ₅ ", and capacitor C _b2 is charged through the circuit of "photovoltaic array-C pv -L 2 -D b2 -S 5 " C _pv -L ₂ -D ₂ - DC side capacitor" loop discharge. Due to the existence of capacitors C _b1 and C _b2 , the voltage drop on switch S ₆ gradually rises from zero, so S ₆ realizes zero-voltage turn-off, and D _b2 and D ₂ realize zero-voltage turn-on. At time t _b , u _b1 rises to u _dc , u _b2 falls to zero, and this switching mode ends. Since the duration of this switching mode is short, it is assumed that the current i _pv flowing through the coupled inductor L _m keeps I _pv (t _a ) constant, and the value of the inductor current i ₁ at time t _a is set to I ₁ (t _a ). Switch modal here:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; PV</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; AZ</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; AZ</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

in:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}\sqrt{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; C</span>}}\\ \mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; PV</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; =</span>\sqrt{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; C</span>}}\\ {\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; L</span>}\\ {\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

The duration t _ba of this switching mode is:

${\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; the\; b</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; sin</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}}{\mathrm{<span\; class="notranslate">\; AZ</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

2) Fig. 3 shows the equivalent circuit diagram of the working mode 2 of the interleaved control high-gain Boost converter. At time t _b , u _b1 is the DC side voltage u _dc , u _b2 is zero, due to the existence of capacitors C _b1 , C _b2 and inductance L ₁ , L ₂ , D ₁ is turned on approximately at zero voltage, and D ₂ is turned off at approximately zero voltage . In this switching mode, i ₁ increases linearly, i ₂ decreases approximately, u _b1 is clamped as u _dc , and u _b2 is clamped as zero. At time _tc , i ₂ drops to zero, and this switching mode ends. Switch modal here:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; Lu</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; PV</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

The duration t _cb of this switching mode is:

${\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; cb</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; Lu</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; PV</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

3) Fig. 4 shows the equivalent circuit diagram of the working mode 3 of the interleaved control high-gain Boost converter. At time t _c , i ₁ rises to be equal to i _pv and i ₂ drops to zero. Due to the existence of capacitors C _b1 , C _b2 and inductors L ₁ , L ₂ , D _b2 , D _b1 are turned off approximately at zero voltage and zero current. In this switching mode, i ₁ is equal to i _pv and rises linearly under the action of the input voltage, i ₂ is zero, u _b1 is u _dc , and u _b2 is zero. At time t _d , S ₆ is turned on, and the switch mode ends. Switch modal here:

i ₁ =I ₁ (t _c )+u _pv (tt _c )/L (6)

The duration of this switching mode t _dc is:

t _dc =t _d -t _c =(1-d)T _s -t _cb -t _ba (7)

4) Fig. 5 shows the equivalent circuit diagram of the working mode 4 of the interleaved control high-gain Boost converter. At time t _d , S ₆ is turned on, i ₁ continues to rise linearly, i ₂ starts to rise linearly from zero, u _b1 keeps u _dc , and u _b2 keeps at zero. Due to the presence of the boost inductor, S ₆ realizes zero-current turn-on. Switch modal here:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; PV</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; PV</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

The duration t _ed of this switching mode is:

t _ed =t _e -t _d =(2d-1)T _s /2 (9)

According to the working principle of the converter, in the first half of the switching cycle, the following two conditions must be met in order to realize soft switching:

1) At time t _c , the current i ₂ needs to drop to zero;

2) At time t _a , the capacitor voltage u _b1 rises to u _dc , and u _b2 drops to zero, requiring:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\\ \mathrm{<span\; class="notranslate">\; AZ</span>}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; dc</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

That's it.

Claims (5)

1., based on the photovoltaic DC-to-AC converter of Interleaved control high-gain Boost, comprise photovoltaic array, Interleaved control high-gain Boost, DC side storage capacitor, full-bridge inverter, LCL filter; Photovoltaic array, Interleaved control high-gain Boost, DC side storage capacitor, full-bridge inverter, LCL filter are connected successively, through circuit breaker access electrical network; Interleaved control high-gain Boost is formed with alternating expression textural association by the Boost circuit of two-way parallel connection, and the inductance in two-way Boost circuit is coupling inductance.

2. the photovoltaic DC-to-AC converter based on Interleaved control high-gain Boost according to claim 1, is characterized in that, Interleaved control high-gain Boost has zero current transfer characteristic.

3. the photovoltaic DC-to-AC converter based on Interleaved control high-gain Boost according to claim 1, is characterized in that, the input current of Interleaved control high-gain Boost is biphase current sum, and input current ripple is little.

4. the photovoltaic DC-to-AC converter based on Interleaved control high-gain Boost according to claim 1, is characterized in that, adopts LCL filter, reduces total inductance amount.

5. the photovoltaic DC-to-AC converter based on Interleaved control high-gain Boost according to claim 1, is characterized in that, the coupling inductance coupling coefficient of Interleaved control high-gain Boost is 0.91.