CN205377662U - Adopt accurate Z source converter of transformer - Google Patents

Abstract

The utility model provides a quasi-Z source converter using a transformer. The converter includes a DC input power supply, a transformer (<i>T</i>) with a turn ratio of 1:<i>n</i>, a first diode (<i>D</i> ₁ ), the first capacitor (<i>C</i> ₁ ), the second capacitor (<i>C</i> ₂ ), the first inductor (<i>L</i> ₁ ), the switch tube ( <i>S</i>), second diode (<i>D</i> ₂ ), output capacitor (<i>C _out </i>) and load. Compared with flyback converters, quasi-Z source converters and the like, the utility model has higher voltage gain, and is suitable for occasions of non-isolated high-gain DC voltage conversion.

Description

A Quasi-Z Source Converter Using Transformer

technical field

The utility model relates to the field of DC/DC converters, in particular to a quasi-Z source converter using a transformer.

Background technique

The development of renewable energy power generation systems such as photovoltaics and fuel cells has become one of the important means to solve the shortage of fossil fuels. However, the output voltage of photovoltaics and fuel cells is very low, and DC/DC converters are generally required to boost the voltage. However, many step-up DC/DC converters are limited by the duty cycle, parasitic parameters and losses, and cannot achieve a large boost. For example, the flyback converter has a voltage gain of nD/(1-D), where n is the transformer Turn ratio, D is the duty cycle, but due to the influence of parasitic parameters, its gain is limited; another example is the quasi-Z source converter, its voltage gain is 1/(1-2D), which has a certain improvement compared with the Boost converter , but there is still room for improvement.

Utility model content

The purpose of this utility model is to overcome the deficiency of above-mentioned prior art, propose a kind of quasi-Z source converter that adopts transformer.

The circuit of the utility model specifically includes a DC input power supply V _in , a transformer with a turn ratio of 1:n, a first diode, a first capacitor, a second capacitor, a first inductor, a switch tube, a second diode, an output capacitance and load.

The specific connection mode of the circuit of the utility model is as follows: the positive pole of the DC input power source V _in is connected to the terminal with the same name on the primary side of the transformer. The opposite end of the primary side of the transformer is connected to the same end of the secondary side of the transformer and one end of the second capacitor. The opposite end of the secondary side of the transformer is connected to the anode of the first diode. The cathode of the first diode is connected with one end of the first capacitor and one end of the first inductor. The other end of the first inductor is connected to the other end of the second capacitor, the drain of the switch tube and the anode of the second diode. The cathode of the second 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 the prior art, the utility model circuit has the advantages that: compared with the traditional flyback converter (its output voltage is ) and a quasi-Z source converter (whose 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 utility model can raise the low-level voltage to a high-level voltage only with a small duty cycle, and the input and output common ground, continuous input current, etc., so the utility model The circuit has a very wide application prospect.

Description of drawings

Figure 1 is a structural diagram of a quasi-Z source converter using a transformer.

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, the flyback converter and the quasi-Z source converter as a function of the duty cycle D.

detailed description

The utility model will be further described in detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is 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 utility model and the reference directions of the voltage and current of each main component are shown in Fig. 1 . For the convenience of analysis, the devices in the circuit structure are regarded as ideal devices. The drive signal v _GS of the switch 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 _L1 of the first inductor L ₁ , the current i _Lm of the excitation inductance L _m of the transformer T , the waveforms of the voltage V _C1 of the first capacitor C ₁ and the voltage V _C2 of the second capacitor C ₂ are shown in FIG. 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 diode D1 and the _second diode D2 are cut off under reverse voltage. The DC input power supply V _in and the _second capacitor C2 charge the excitation inductance L _m of the transformer T through the switch tube S at the same time, and the first capacitor _C1 charges the _first inductor L1 through the switch tube S at the same time. 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. _The diode D1 and the _second diode D2 are turned on under forward voltage. The DC input power supply V _in and the excitation inductance L _m of the transformer T simultaneously charge the first capacitor C ₁ through the first diode D ₁ , and the DC input power supply V _in and the excitation inductance L _m of the transformer T pass through the second diode D ₂ Simultaneously charge the second capacitor C ₂ , the output capacitor C _out and the load, the first inductor L ₁ charges the second capacitor C ₂ through the first diode D ₁ , and the first inductor L ₁ passes through the second diode D ₂ Charge the first capacitor C ₁ , the output capacitor C _out and the load. In addition, the DC input power supply V _in , the excitation inductance L _m of the transformer T and the first inductance L ₁ simultaneously charge the output capacitor C _out and the load through the first diode D ₁ and the second diode D ₂ .

The steady-state gain of the utility model circuit is derived as follows.

Since the average value of the voltages of the first inductance L ₁ and the excitation inductance L _m of the transformer T is zero within one switching cycle, the following relationship can be obtained.

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

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

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

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

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

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

The steady-state gains of the traditional flyback converter and the quasi-Z source converter are respectively nD/(1-D) and 1/(1-2D) (D is the duty cycle). When the turn ratio n=3, the practical The steady-state gain comparison diagram of the novel proposed circuit and the flyback converter and the 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 utility model only needs the duty cycle If it is 0.18, it can rise to about 100V, while the other two converters require a larger duty cycle.

Claims (1)

1. A quasi-Z source converter using a transformer, characterized in that it includes a DC input power supply, a transformer ( T ) with a turn ratio of 1: n , a first diode ( D ₁ ), and a first capacitor ( C ₁ ) , the second capacitor ( C ₂ ), the first inductor ( L ₁ ), the switch tube ( S ), the second diode ( D ₂ ), the output capacitor ( C _out ) and the load; The positive pole of the DC input power supply is connected to the terminal with the same name on the primary side of the transformer ( T ); The opposite end of the primary side of the transformer ( T ) is connected to the same end of the secondary side of the transformer ( T ) and one end of the second capacitor ( C ₂ ); the opposite end of the secondary side of the transformer ( T ) is connected to the first The anode of a diode ( D ₁ ) is connected; the cathode of the first diode ( D ₁ ) is connected with one end of the first capacitor ( C ₁ ) and one end of the first inductor ( L ₁ ); the The other end of the first inductor ( L ₁ ) is connected to the other end of the second capacitor ( C ₂ ), the drain of the switch tube ( S ) and the anode of the second diode ( D ₂ ); the second The cathode of the diode ( D ₂ ) is connected to one end of the output capacitor ( C _out ) and 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 is connected to the first capacitor ( The other end of C ₁ ), the source of the switch tube ( S ), the other end of the output capacitor ( C _out ) and the other end of the load are connected.