CN105490530A - Quasi Z source converter employing switched inductor and voltage lifting technique - Google Patents

Abstract

The invention provides a quasi-Z source converter adopting switching inductance and voltage lifting technology. The converter includes a DC input power source <i>V _in </i>, a first diode (<i>D</i> ₁ ), a first inductor (<i>L</i> ₁ ), Second diode (<i>D</i> ₂ ), second inductor (<i>L</i> ₂ ), third diode (<i>D</i> ₃ ), second Second capacitor (<i>C</i> ₂ ), fourth diode (<i>D</i> ₄ ), first capacitor (<i>C</i> ₁ ), fifth diode tube (<i>D</i> ₅ ), third capacitor (<i>C</i> ₃ ), third inductor (<i>L</i> ₃ ), fourth inductor (<i>L</i> ₄ ), sixth diode (<i>D</i> ₆ ), switch tube (<i>S</i>), seventh diode (<i>D</i>i> ₇ ), the output capacitor (<i>C _out </i>) and the load. Compared with Boost converters, switch inductance type quasi-Z source converters and the like, the invention has higher voltage gain, and is suitable for the occasion of non-isolated high-gain DC voltage conversion.

Description

A Quasi-Z Source Converter Using Switched Inductor and Voltage Lifting Technique

technical field

The invention relates to the field of DC/DC converters, in particular to a quasi-Z source converter using switching inductance and voltage lifting technology.

Background technique

In recent years, with the depletion of fossil energy such as petroleum and coal, countries all over the world are vigorously developing new renewable clean energy, such as solar energy, fuel cells and wind energy. Renewable energy power generation systems usually require a DC power converter with strong boost capability to convert the low-voltage DC (18-50V) obtained from renewable energy into a high enough DC voltage (200-400V), and then Invert to generate electricity on the grid. However, many step-up DC/DC converters are limited by parasitic parameters, heat generation and loss, and cannot achieve a large boost. For example, the Boost converter has a voltage gain of 1/(1-D), where D is the duty cycle , but due to the influence of parasitic parameters, its gain is limited; another example is the dual-switch inductive quasi-Z source converter, its voltage gain is (1+D)/(1-3D), which has a great improvement compared with the Boost converter improved, but there is still room for improvement.

Contents of the invention

The object of the present invention is to overcome the shortcomings of the above-mentioned prior art, and propose a quasi-Z source converter using switched inductance and voltage boosting technology.

The circuit of the present invention specifically includes a DC input power supply V _in , a first diode, a first inductance, a second diode, a second inductance, a third diode, a second capacitor, a fourth diode, a first Capacitor, fifth diode, third capacitor, third inductor, fourth inductor, sixth diode, switch tube, seventh diode, output capacitor and load.

The specific connection mode of the circuit of the present invention is as follows: the anode of the DC input power supply V _in is connected to the anode of the first diode and one end of the first inductor. The cathode of the first diode is connected with the cathode of the second diode and one end of the second inductance. The anode of the second diode is connected with the other end of the first inductor and the anode of the third diode. The other end of the second inductor is connected to the cathode of the third diode, one end of the second capacitor and the anode of the fourth diode. The cathode of the fourth diode is connected with one end of the first capacitor, the anode of the fifth diode and one end of the third inductor. The cathode of the fifth diode is connected with one end of the third capacitor and one end of the fourth inductor. The other end of the third capacitor is connected to the other end of the third inductor and the anode of the sixth diode. The cathode of the sixth diode is connected with the other end of the fourth inductance, the other end of the second capacitor, the drain of the switch tube and the anode of the seventh diode. The cathode of the seventh diode is connected with one end of the output capacitor and one end of the load. The output capacitor is connected in parallel with the load. The negative pole of the DC input power supply _Vin is connected to the other end of the first capacitor, the source of the switch tube, the other end of the output capacitor and the other end of the load.

Compared with prior art, the advantage that circuit of the present invention has is: compared with traditional Boost converter (its output voltage is ) and a two-switch inductive quasi-Z source converter (its output voltage is ) and other DC/DC converters, in the case of the same duty cycle and input voltage, have a higher output voltage, the output voltage is Under the same input voltage and output voltage conditions, the circuit of the present invention can raise the low-level voltage to a high-level voltage only with a small duty cycle, and the input and output share the same ground, so the circuit of the present invention has a wide range of applications prospect.

Description of drawings

Figure 1 is a structural diagram of a quasi-Z source converter using switched inductors and voltage boost technology.

Figure 2 is a voltage and current waveform diagram of the main components of a switching cycle.

Figure 3a and Figure 3b are circuit modal diagrams in a switching cycle.

Fig. 4 is the waveform diagram of the gain V _out /V _in of the proposed circuit, Boost and dual-switch inductive quasi-Z source converters as a function of the duty cycle D.

detailed description

The present invention will be described in further detail in conjunction with the following examples and accompanying drawings, but the embodiments of the present invention are not limited thereto. It should be noted that, if there are any processes or parameters that are not specifically described in detail below, those skilled in the art can understand or implement them with reference to the prior art.

The basic topological structure of the present invention and the reference directions of voltage and current of each main component are shown in FIG. 1 . For the convenience of verification, the devices in the circuit structure are regarded as ideal devices. The drive signal v _GS of the switching tube S, the current i D1 of the first diode D ₁ , the current i _D2 of the second diode D ₂ , the current i _D3 of the third diode D ₃ , the current i _D 4 of the fourth diode D ₄ i _D4 , fifth diode D ₅ current i _D5 , sixth diode D ₆ current i _D6 , seventh diode D ₇ current i _D7 , first inductor L ₁ current i _L1 , second inductor L _{2 Waveforms} of current i _L2 , current i L3 of the third inductor L ₃ , current i _L4 of the fourth inductor L ₄ , voltage V _C1 of the first capacitor C ₁ , voltage V _C2 of the second capacitor C ₂ , and voltage V _C3 of the third capacitor C ₃ The picture is shown in Figure 2.

In the t ₀ ~ t ₁ stage, the modal diagram of the converter at this stage is shown in Figure 3a, the driving signal v _GS of the switch tube S changes from low level to high level, the switch tube S is turned on, and the first two The pole diode D ₁ , the third diode D ₃ , the fifth diode D ₅ and the sixth diode D ₆ are subjected to forward voltage conduction, and the second diode D ₂ and the fourth diode D ₄ And the _seventh diode D7 withstands the reverse voltage cut-off. The DC input power V _in and the second capacitor C ₂ charge the second inductor L ₂ simultaneously through the first diode D ₁ and the switch tube S, and the DC input power V _in and the second capacitor C ₂ pass through the third diode D ₃ and the switch tube S charge the first inductor L ₁ at the same time, the first capacitor C ₁ charges the fourth inductor L 4 through the fifth diode D ₅ and the switch tube S, and the first capacitor C ₁ charges the fourth inductor L ₄ through the sixth diode D ₆ and the switch tube S charge the third inductor L ₃ , and the first capacitor C ₁ charges the third capacitor C ₃ through the fifth diode D ₅ , the sixth diode D ₆ and the switch tube S. In addition, the output capacitor C _out supplies power to the load.

In the stage t ₁ ~ t ₂ , the modal diagram of the converter at this stage is shown in Figure 3b. The driving signal v _GS of the switch tube S changes from high level to low level, and the switch tube S is turned off. Diode D ₁ , third diode D ₃ , fifth diode D ₅ and sixth diode D ₆ are cut off under reverse voltage, and second diode D ₂ , fourth diode D ₄ and The seventh diode D ₇ is turned on under forward voltage. The DC input power supply V _in and the first inductor L ₁ and the second inductor L ₂ simultaneously supply the first capacitor C ₁ and the second capacitor C 1 through the second diode D ₂ , the fourth diode D ₄ and the seventh diode D ₇ The second capacitor C ₂ , the output capacitor C _out and the load are charged, and the third inductance L ₃ , the fourth inductance L ₄ and the third capacitor C ₃ simultaneously charge the first capacitor through the fourth diode D ₄ and the seventh diode D ₇ The capacitor C ₁ , the second capacitor C ₂ , the output capacitor C _out and the load are charged. In addition, the DC input power supply V _in , the first inductor L ₁ , the second inductor L ₂ , the third inductor L ₃ , the fourth inductor L ₄ and the third capacitor C ₃ pass through the second diode D ₂ , the fourth diode _The tube D4 and the _seventh diode D7 supply power to the output capacitor C _out and the load at the same time.

The steady-state gain of the circuit of the present invention is derived as follows.

Since the inductance values of the _first inductance L1 and the _second inductance L2 are equal, and the inductance values of the _third inductance L3 and the _fourth inductance L4 are equal, the voltage and current of the _first inductance L1 and the _second inductance L2 are equal , the voltage and current of the _third inductor L3 and the _fourth inductor L4 are equal.

Since the average value of the voltages of the first inductor L ₁ , the second inductor L ₂ , the third inductor L ₃ , and the fourth inductor L ₄ is zero within one switching cycle, the following relationship can be obtained.

$<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

And when the switch tube (S) is turned off, the output voltage V _out satisfies the following relationship.

V _out =V _C1 +V _C2 (3)

Simultaneously solving equations (1), (2) and (3) can obtain the relationship between the output voltage V _out and the DC input voltage V _in .

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

The steady-state gains of the traditional Boost converter and the double-switch inductance type quasi-Z source converter are respectively 1/(1-D) and (1+D)/(1-3D) (D is the duty cycle), and the present invention The steady-state gain comparison diagram of the proposed circuit and the Boost converter and the switched inductance type quasi-Z source converter is shown in Figure 4, as can be seen from Figure 4, when the input voltage is 10V, the circuit proposed by the present invention only needs a duty cycle of 0.2 can rise to about 150V, while the other two converters require a larger duty cycle.

Claims (2)

1. A quasi-Z source converter using switched inductance and voltage boosting technology, characterized in that it includes a DC input power supply, a first diode ( D ₁ ), a first inductance ( L ₁ ), and a second diode ( D ₂ ), the second inductor ( L ₂ ), the third diode ( D ₃ ), the second capacitor ( C ₂ ), the fourth diode ( D ₄ ), the first capacitor ( C ₁ ), the second capacitor Five diodes ( D ₅ ), third capacitor ( C ₃ ), third inductance ( L ₃ ), fourth inductance ( L ₄ ), sixth diode ( D ₆ ), switch tube ( S ), the first Seven diode ( D ₇ ), output capacitor ( C _out ) and load; The anode of the DC input power supply is connected to the anode of the first diode ( D ₁ ) and one end of the first inductor ( L ₁ ); the cathode of the first diode ( D ₁ ) is connected to the second diode The cathode of ( D ₂ ) is connected to one end of the second inductor ( L ₂ ); the anode of the second diode ( D ₂ ) is connected to the other end of the first inductor ( L ₁ ) and the third diode ( D ₃ ) anode connection; the other end of the second inductor ( L ₂ ) is connected to the cathode of the third diode ( D ₃ ), one end of the second capacitor ( C ₂ ) and the fourth diode ( D ₄ ) The anode of the fourth diode ( D ₄ ) is connected to the cathode of the first capacitor ( C ₁ ), the anode of the fifth diode ( D ₅ ) and one end of the third inductor ( L ₃ ) ; The cathode of the fifth diode ( D ₅ ) is connected to one end of the third capacitor ( C ₃ ) and one end of the fourth inductor ( L ₄ ); the other end of the third capacitor ( C ₃ ) is connected to the first end The other end of the third inductor ( L ₃ ) is connected to the anode of the sixth diode ( D ₆ ); the cathode of the sixth diode ( D ₆ ) is connected to the other end of the fourth inductor ( L ₄ ), the second The other end of the capacitor ( C ₂ ), the drain of the switch tube ( S ) is connected to the anode of the seventh diode ( D ₇ ); the cathode of the seventh diode ( D ₇ ) is connected to the output capacitor ( C _out ) is connected to one end of the load; the output capacitor ( C _out ) is connected in parallel with the load; the negative pole of the DC input power supply V _in is connected to the other end of the first capacitor ( C ₁ ) and the source of the switch tube ( S ) , The other end of the output capacitor ( C _out ) is connected to the other end of the load. 2. a kind of quasi-Z source converter that adopts switched inductance and voltage lift technology according to claim 1 is characterized in that the relationship between output voltage V _out and DC input voltage V _in is: , D is the duty cycle.