CN216016717U

CN216016717U - quasi-Z-source DC-DC converter integrating switch capacitor and coupling inductor

Info

Publication number: CN216016717U
Application number: CN202121906198.1U
Authority: CN
Inventors: 王凤莲; 曹益畅; 周明珠; 韦正怡; 薛鹏飞; 叶睿明; 赵振伟; 袁成功; 张民
Original assignee: Qingdao University of Technology
Current assignee: Qingdao University of Technology
Priority date: 2021-08-16
Filing date: 2021-08-16
Publication date: 2022-03-11
Anticipated expiration: 2031-08-16

Abstract

The utility model belongs to the technical field of DC-DC conversion equipment, and relates to a quasi Z-source DC-DC converter integrating a switch capacitor and a coupling inductor, which comprises a direct-current power supply, a coupling inductor unit, a quasi Z-source module, a switch capacitor module and a switch module, wherein the coupling inductor module is provided with mutually coupled windings, the step-up conversion of output voltage to the voltage of the direct-current power supply is realized by changing the turn ratio of the coupling windings, the condition of limit duty ratio can be effectively avoided, the conversion function of high output voltage is realized by using smaller duty ratio, and the switch capacitor module can improve the voltage gain, reduce the power loss and improve the circuit efficiency through a parallel charging and series discharging structure; the structure is reasonable in overall design, safe to use, simple to operate and has great application potential.

Description

quasi-Z-source DC-DC converter integrating switch capacitor and coupling inductor

Technical Field

The utility model belongs to the technical field of DC-DC conversion equipment, and relates to a quasi-Z-source DC-DC converter integrating a switched capacitor and a coupling inductor.

Background

In recent years, in order to solve the problems of ecological environment protection and non-renewable energy crisis, a distributed power generation system formed by renewable and clean energy is developed rapidly. In practical application, the electric energy conversion circuit structures have the characteristics of high efficiency, high boost gain and the like, but because the boost capability of a single module is too low in the energy conversion process, higher output voltage cannot be obtained. For example, a photovoltaic power supply is one of widely-used clean energy sources, but because the output voltage of a single photovoltaic panel is low (18-56V), sufficient voltage cannot be provided for a later-stage inversion grid-connected device, one of the solutions is to use the photovoltaic panels in series and parallel connection to improve the voltage level and the power level, but the failure rate of the system is increased, and the failure of one photovoltaic panel can cause the whole system to fail to operate normally.

Therefore, how to obtain a stable high-gain output voltage by using an independent module becomes a problem to be solved urgently. In the existing research, the traditional topological structures such as Boost, Buck-Boost, Sepic and the like are simple in structure and easy to control, but the topologies cannot achieve high and ideal voltage gain and high efficiency, and the purpose of boosting is achieved by needing a circuit to work at a limit duty ratio for a long time, which is difficult to achieve. Aiming at the problem, cascade connection can be carried out through a multi-stage circuit, and higher voltage gain is obtained under the condition of smaller through duty ratio. But the number of components in the circuit is increased, the complexity of the circuit is improved, the design cost is increased, and the working efficiency is reduced. With the development in recent years, some topologies which are added with modules such as a switching inductor and a coupling inductor to realize high boosting capacity are developed, but due to the existence of leakage inductance and the requirement of high power in practical occasions, the topologies of the type have the problems of large voltage stress of devices such as a switching tube and the like, and the high-voltage high-power electronic devices are expensive, so that the manufacturing cost of the whole topology is undoubtedly increased greatly. Therefore, finding a DC-DC conversion circuit that can obtain a higher boost gain at a lower through duty ratio, and has a simple structure and high operating efficiency has become a research hotspot in the field.

SUMMERY OF THE UTILITY MODEL

Aiming at the technical defects existing in the existing research situation, the utility model provides the quasi-Z-source DC-DC converter integrating the switched capacitor and the coupling inductor, which can obtain higher voltage gain under the condition of small direct duty ratio, and meanwhile, the circuit structure has the advantages of relatively few used devices, high working efficiency, low failure rate and effective practical application.

In order to achieve the purpose, the quasi Z-source DC-DC converter integrating the switch capacitor and the coupling inductor comprises a direct-current power supply, a quasi Z-source module, a coupling inductor module, a switch capacitor module and a switching module, wherein the direct-current power supply is connected with the quasi Z-source module, and a first capacitor, a second capacitor, a first diode and the switching module of the quasi Z-source module form a switch tube clamping loop so as to reduce voltage spikes on a switch tube; the coupling inductance module consists of a first coupling inductance and a second coupling inductance which are well coupled with each other, the turn ratio of the two coupling inductances is 1: n, and a coupling inductance turn ratio influence factor can be injected into a boosting factor, so that the condition of limit duty ratio is effectively avoided, and the change of output voltage gain under the lower direct duty ratio can be realized by adjusting the size of the duty ratio and the turn ratio of a coupling winding; the input end of the switched capacitor module is connected with the second coupling inductor, the output end of the switched capacitor module is connected with the anode of the diode, the cathode of the diode is connected with the capacitor and the load in parallel, the capacitor and the load are used for improving voltage gain, and due to the low ESR characteristic of the capacitor, the topological power loss can be reduced, and the circuit efficiency is improved; the switch switching module switches the working state of the circuit by controlling the on-off of the switch tube.

Further, the quasi-Z source module is composed of an input inductor, a first diode, a first capacitor and a second capacitor: one end of the input inductor is connected with the positive electrode of the direct-current power supply, and the other end of the input inductor is respectively connected with the anode of the first diode and the negative electrode of the second capacitor; the cathode of the first diode is respectively connected with the dotted terminal of the first coupling inductor and the anode of the first capacitor, and the anode of the first diode is connected with the cathode of the second capacitor; the positive electrode of the first capacitor is connected with the dotted terminal of the first coupling inductor, and the negative electrode of the first capacitor is grounded; the positive electrode of the second capacitor is respectively connected with the synonym end of the first coupling inductor and the synonym end of the second coupling inductor.

Further, the switched capacitor module is composed of a third capacitor, a fourth capacitor, a second diode, and a third diode: the anode of the second diode is respectively connected with the synonym end of the second coupling inductor and the cathode of the third capacitor, and the cathode of the second diode is respectively connected with the anode of the third diode and the anode of the fourth capacitor; the anode of the third diode is respectively connected with the cathode of the second diode and the anode of the fourth capacitor, and the cathode of the third diode is respectively connected with the anode of the third capacitor and the anode of the diode; the anode of the third capacitor is connected with the anode of the diode, and the cathode of the third capacitor is connected with the synonym end of the second coupling inductor; the negative pole of the fourth capacitor is grounded.

Furthermore, the switching module is composed of a switch tube, a drain electrode of the switch tube is respectively connected with the synonym end of the first coupling inductor, the homonym end of the second coupling inductor and the anode of the second capacitor, and a source electrode of the switch tube is grounded.

The utility model adopts a PWM control mode to realize the switching control of the switch module, and can control the on-off of the switch tube S to realize the switching of different working states of the circuit through the change of the duty ratio.

Compared with the existing DC-DC boost converter circuit topological structure, the utility model integrates the switch capacitor, the coupling inductor and the quasi-Z source, improves the voltage gain by utilizing the switch capacitor and the coupling inductor structure, and can realize the purpose of obtaining high boost gain under the condition of small duty ratio by adjusting the turn ratio of the coupling inductor winding; in addition, the voltage clamping of the switching tube is realized by utilizing the quasi-Z source structure, the loss of the switching tube is reduced, and the efficiency of the converter is improved; the circuit has the advantages of reasonable overall structural design, safety in use, simplicity in operation, great application potential, higher voltage gain, improvement of the working efficiency of the circuit and basically ideal effect of design requirements.

Drawings

Fig. 1 is a schematic diagram of the main circuit structure of the present invention.

Fig. 2 is a schematic diagram of the working state of the circuit when the switching tube S of the present invention is turned on.

Fig. 3 is a schematic diagram of the working state of the circuit when the switching tube S of the present invention is turned off.

The specific implementation mode is as follows:

in order to more specifically describe the present invention, the following description is given with reference to the accompanying drawings.

Example 1:

in this embodiment, a quasi-Z source DC-DC converter structure integrating a switched capacitor and a coupled inductor is shown in fig. 1, and includes: DC power supply V_gAn input inductor L₁A first coupling inductor L_2aA second coupling inductor L_2bSwitch tube S and first diode D₁A second diode D₂A third diode D₃Diode D_oCapacitor C_oA first capacitor C₁A second capacitor C₂A third capacitor C₃A fourth capacitor C₄And a load R; the coupling inductance module is composed of two first coupling inductors L which are well coupled with each other_2aAnd a second coupling inductor L_2bThe turn ratio of the two coupled inductors is 1: n, and the input inductor L₁One end of the DC power supplyV_gThe other end of the anode is respectively connected with a first diode D₁And a second capacitor C₂The negative electrode of (1) is connected; first diode D₁Respectively with the first coupling inductor L_2aEnd of same name and first capacitor C₁Is connected with the anode of the second capacitor C₂The negative electrode of (1) is connected; a first capacitor C₁And the positive electrode of the first coupling inductor L_2aThe same name end of the anode is connected with the ground, and the cathode is grounded; second capacitor C₂Respectively with the first coupling inductor L_2aEnd of different name, second coupling inductance L_2bThe homonymous terminals of the two terminals are connected; second diode D₂Respectively with the second coupling inductors L_2bAnd a third capacitor C₃Is connected with the cathode of the third diode D₃Anode and fourth capacitor C₄The positive electrode of (1) is connected; third diode D₃Respectively with the second diode D₂Cathode and fourth capacitor C₄Is connected with the anode and the cathode is respectively connected with a third capacitor C₃Anode and diode D_oThe anode of (2) is connected; diode D₀The cathode is connected in parallel with a capacitor C₀And a load R; third capacitor C₃Anode and diode D_oIs connected with the anode, and the cathode is connected with the second coupling inductor L_2bThe different name ends of the two groups are connected; fourth capacitor C₄The negative electrode of (2) is grounded; the drain electrodes of the switch tubes S are respectively connected with the first coupling inductors L_2aEnd of different name, second coupling inductance L_2bEnd of same name and second capacitor C₂The anode of the transistor is connected with the source electrode of the transistor, and the source electrode of the transistor is grounded.

In this embodiment, the quasi-Z source DC-DC converter integrating the switched capacitor and the coupled inductor has two operating states of a direct-connection state and a non-direct-connection state in a continuous operating mode:

through state (fig. 2): when the switch tube S is conducted, the third diode D₃Forward conduction, the first diode D₁A second diode D₂Diode D_oReverse cut-off, DC power supply V_gAnd a second capacitor C₂The energy is transferred to the input inductor L through the switch tube S₁(ii) a Fourth capacitor C₄Through a third diode D₃To a firstThree capacitors C₃Charging; a first capacitor C₁The first coupling inductor L is supplied by the switch tube S_2aProviding capability while the second coupling inductance L_2bStoring energy through a primary side; capacitor C_oIs large enough to provide energy to the load R and the voltage across the load R remains substantially constant.

Non-pass through state (fig. 3): when the switch tube S is turned off, the first diode D₁A second diode D₂Diode D_oForward conducting, third diode D₃Reverse cut-off when the DC power supply V_gAn input inductor L₁A first coupling inductor L_2aA second coupling inductor L_2bAnd a third capacitor C₃Together provide energy to a load R, while a first capacitor C₁Through a first diode D₁Charging, first coupling inductor L_2aThrough a first diode D₁Is a second capacitor C₂Charging, fourth capacitor C₄Through a second diode D₂And (6) charging.

In this embodiment, in order to simplify the analysis, the leakage inductance on the coupling inductor is ignored in the steady-state analysis, the transformer is an ideal transformer, and the turn ratio of the coupling winding is N ═ N₂:N₁Meanwhile, the loss of the power device is not considered, and the gain of the quasi-Z-source DC-DC converter integrating the switched capacitor and the coupling inductor under CCM can be obtained through the KVL law and the inductor volt-second equilibrium law:

the quasi-Z-source DC-DC converter integrating the switched capacitor and the coupling inductor is tested under the test conditions that the input voltage and the output voltage meet the boost gain and the converter power is 200W, the overall working efficiency of the whole circuit can reach about 95%, and the design requirement is basically met.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.

Claims

1. A quasi-Z source DC-DC converter integrating a switch capacitor and a coupling inductor is characterized in that: the switching circuit comprises a direct current power supply, a quasi Z source module, a coupling inductor module, a switch capacitor module and a switching module, wherein the direct current power supply is connected with the quasi Z source module, and a first capacitor, a second capacitor, a first diode and the switching module of the quasi Z source module form a switching tube clamping loop; the coupling inductance module consists of a first coupling inductance and a second coupling inductance, and the turn ratio of the two coupling inductances is 1: n; the input end of the switch capacitor module is connected with the second coupling inductor, the output end of the switch capacitor module is connected with the anode of the diode, and the cathode of the diode is connected with the capacitor and the load in parallel.

2. The integrated switched capacitor and coupled inductor quasi-Z source DC-DC converter of claim 1, wherein: the quasi-Z source module consists of an input inductor, a first diode, a first capacitor and a second capacitor: one end of the input inductor is connected with the positive electrode of the direct-current power supply, and the other end of the input inductor is respectively connected with the anode of the first diode and the negative electrode of the second capacitor; the cathode of the first diode is respectively connected with the dotted terminal of the first coupling inductor and the anode of the first capacitor, and the anode of the first diode is connected with the cathode of the second capacitor; the positive electrode of the first capacitor is connected with the dotted terminal of the first coupling inductor, and the negative electrode of the first capacitor is grounded; the positive electrode of the second capacitor is respectively connected with the synonym end of the first coupling inductor and the synonym end of the second coupling inductor.

3. The integrated switched capacitor and coupled inductor quasi-Z source DC-DC converter of claim 1, wherein: the switch capacitor module is composed of a third capacitor, a fourth capacitor, a second diode and a third diode: the anode of the second diode is respectively connected with the synonym end of the second coupling inductor and the cathode of the third capacitor, and the cathode of the second diode is respectively connected with the anode of the third diode and the anode of the fourth capacitor; the anode of the third diode is respectively connected with the cathode of the second diode and the anode of the fourth capacitor, and the cathode of the third diode is respectively connected with the anode of the third capacitor and the anode of the diode; the anode of the third capacitor is connected with the anode of the diode, and the cathode of the third capacitor is connected with the synonym end of the second coupling inductor; the negative pole of the fourth capacitor is grounded.

4. The integrated switched capacitor and coupled inductor quasi-Z source DC-DC converter of claim 1, wherein: the switching module is composed of a switch tube, the drain electrode of the switch tube is respectively connected with the synonym end of the first coupling inductor, the homonymy end of the second coupling inductor and the anode of the second capacitor, and the source electrode of the switch tube is grounded.