CN206211838U - A kind of quasi- Z sources DC DC converters of coupling inductance type - Google Patents

Abstract

The utility model provides a kind of quasi- Z sources DC DC converters of coupling inductance type, including direct-current input power supplying, the first inductance（L ₁）, the first diode（D ₁）, the first electric capacity（C ₁）, the second electric capacity（C ₂）, the turn ratio be 1:nTransformer（T）, switching tube（S）, the second diode（D ₂）, output capacitance（C _out ）And load.The utility model is compared to anti exciting converter, quasi- Z source converters etc. with voltage gain higher, it is adaptable to the occasion of non-isolation type high-gain DC voltage transformation.

Description

A Coupled Inductor Quasi-Z Source DC-DC Converter

technical field

The invention relates to the field of DC/DC converters, in particular to a coupled inductance quasi-Z source DC-DC converter.

Background technique

In recent years, photovoltaic power generation technology has achieved unprecedented development, and it has also become one of the main utilization methods of solar energy. Photovoltaic grid-connected power generation technology is of great significance to alleviate the energy crisis, protect the environment and ensure sustainable economic development. Usually, the output voltage of the photovoltaic array battery is low, and it must be boosted by a DC/DC converter to meet the requirements of the grid-connected inverter, so the DC/DC converter is required to have higher gain and efficiency. 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 it is still difficult to meet the needs of practical applications.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, and propose a coupled inductance type quasi-Z source DC-DC converter.

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

The specific connection mode of the circuit of the present invention is: the positive pole of the DC input power supply is connected to one end of the first inductor. The other end of the first inductor is connected with one end of the second capacitor and the anode of the first diode. The cathode of the first diode is connected with one end of the first capacitor and the same-named end of the primary side of the transformer. The other end of the second capacitor is connected to the opposite end of the secondary side of the transformer. The opposite terminal of the primary side of the transformer is connected with the same terminal of the secondary side of the transformer, 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 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 advantage that the circuit of the present invention has is: 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 present invention 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 circuit of the present invention has the advantages of Very broad application prospects.

Description of drawings

Figure 1 is a structural diagram of a coupled inductance quasi-Z source DC-DC converter.

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 at different stages within a switching cycle.

Fig. 4 is a waveform diagram of the gain V _out /V _in of the circuit of the present invention, the flyback converter and the quasi-Z source converter changing with the duty ratio D in the example.

detailed description

The present invention will be described in further detail below in conjunction with the embodiments 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 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 .

(1) During 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, and the switch tube S is turned on. The _first diode D1 and the _second diode D2 are cut off under reverse voltage. The DC input power supply V _in and the second capacitor C ₂ charge the first inductor L ₁ through the first diode D ₁ and the switch tube S at the same time, and the first capacitor C ₁ charges the excitation inductance L _m of the transformer T through the switch tube S . In addition, the output capacitor C _out supplies power to the load.

(2) During the t ₁ ~ t ₂ stage, the modal diagram of the converter at this stage is shown in Fig. 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 _first diode D1 and the _second diode D2 are turned on under forward voltage. The DC input power supply V _in and the first inductor L ₁ charge the first capacitor C 1 through the first diode D ₁ at the same time, and the DC input power supply V _in and the first inductor L _{1 simultaneously charge the first capacitor C 1 through} the second diode D ₂ The second capacitor C ₂ , the output capacitor C _out and the load are charged, the excitation inductance L _m of the transformer T charges the second capacitor C ₂ through the first diode D ₁ , and the excitation inductance L _m of the transformer T 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 source V _in , the first inductor L ₁ and the excitation inductor L _m of the transformer T 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 circuit of the present invention 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.

(V _in +V _C2 +nV _C1 )t _on +(V _in -V _C1 )t _off ＝0 (1)

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

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

The steady-state gains of the traditional flyback converter and the quasi-Z source converter are nD/(1-D) and 1/(1-2D) respectively (D is the duty cycle, n is the transformer turn ratio), when the turn ratio n =3, the steady-state gain comparison diagram of the proposed circuit of the present invention 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 present invention only It can be raised to about 100V with a duty cycle of 0.18, while the other two converters require a larger duty cycle.

Claims (1)

1. A coupled inductance type quasi-Z source DC-DC converter is characterized in that comprising a DC input power supply, a first inductance (L ₁), the first diode (D. ₁), the first capacitor (C ₁), the second capacitor (C ₂), the turns ratio is 1:no of the transformer (T ),turning tube(S ), the second diode (D. ₂), the output capacitance (C _out ) and load; The positive pole of the DC input power supply is connected to the first inductor (L ₁) is connected at one end; the first inductor (L ₁) and the other end of the second capacitor (C ₂) at one end and the first diode (D. ₁) to the anode connection; the first diode (D. ₁) of the cathode with the first capacitor (C ₁) at one end and the transformer (T ) The same-named end of the primary side is connected; the second capacitor (C ₂) with the other end of the transformer (T ) the opposite side of the secondary side is connected; the transformer (T ) of the opposite side of the primary side with the transformer (T ) The terminal with the same name on the secondary side, the switch tube (S ) drain and the second diode (D. ₂) to the anode connection; the second diode (D. ₂) of the cathode and the output capacitance (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 is connected to the first capacitor (C ₁), the other end of the switch tube (S ), the source of the output capacitance (C _out ) is connected to the other end of the load.