CN103312153B - A kind of parallel multi input coupling inductance buck-boost converter - Google Patents

Abstract

The invention discloses a parallel multi-input coupled inductance buck-boost converter, which belongs to the technical field of power electronic conversion. The converter is composed of N step-up circuits, a step-down circuit (20) and a load, N is a natural number greater than 1, and each step-up circuit is composed of an input source, a filter inductor, a switch tube, a diode and a filter Composed of capacitors, the step-down circuit is composed of a switch tube, a diode, a filter inductor and a filter capacitor, the output ends of N booster circuits are connected in parallel, and then connected to the input ends of the step-down circuit (20), and the step-down circuit (20) The output end is connected to the load, and the filter inductances of the N step-up circuits are respectively coupled with the filter inductances of the step-down circuits. The converter of the present invention can realize multiple input sources supplying power to the load at the same time, and can realize the buck-boost conversion between the input and output, the filter inductance is coupled to each other, the converter is small in size, and different input sources and load sides can be independently controlled. Controls are simple.

Description

A Parallel Multi-Input Coupled Inductor Buck-Boost Converter

technical field

The invention relates to a parallel multi-input coupled inductance buck-boost converter, which belongs to the technical field of power electronic converters, and particularly relates to the technical field of power converters in the technical field of new energy power generation.

Background technique

With the increasingly serious energy crisis and environmental pollution, the development and utilization of solar energy, wind energy, fuel cells and other new and renewable energy sources have received more and more attention. Distributed power generation systems have become a focus of attention and research in countries all over the world. However, the inherent defects of new energy power generation equipment have brought some new problems and challenges, such as: the response speed of the fuel cell is relatively slow, and the output power cannot track the change of the load in time; Due to the influence of changes in natural conditions such as ambient temperature, it is impossible to continuously and stably output electric energy, which leads to an increase in system stability problems. Therefore, in order to ensure continuous and reliable power supply to loads, it is often necessary to combine multiple new energy sources with complementary advantages to form a joint distributed power supply system.

Since the distributed power supply system contains multiple input sources, the voltage of each input source is not stable, so a direct-to-direct conversion is required to convert the relatively unstable output voltage of the input source into a stable voltage for the load. Straight-to-straight converters can be divided into two categories according to the number of input sources: single-input straight-to-straight converters and multi-input straight-to-straight converters. In some occasions with small and medium power and where new energy power generation devices are close, if multiple single-input DC-to-DC converters are used, the structure will become complicated and the cost will be high. In this case, a multi-input DC-DC converter can be used instead of multiple single-input DC-DC converters. In addition, the output voltage of new energy power generation equipment such as thermal energy temperature difference battery, photovoltaic battery, and fuel cell changes in a wide range with changes in environmental conditions, while energy storage equipment such as batteries and supercapacitors change according to different charging and discharging states. The terminal voltage is also changed in a wide range, so a buck-boost straight-to-direct converter that can adapt to a wide range of input voltage changes is required.

Among the buck-boost converters, the buck-boost converter composed of Buck converter and Boost converter cascaded has gained more research and application because of its many advantages. The literature "Ren Xiaoyong, Tang Zhao, Ruan Xinbo, etc. A novel four-switch Buck-Boost converter [J]. Chinese Journal of Electrical Engineering, 2008, 28(21): 15-19." The Buck converter studied The buck-boost converter cascaded with the Boost converter contains only one inductor and has a simple topology, but the current at the input and output terminals is intermittent, so it is not suitable for applications that are sensitive to ripples such as thermal energy thermoelectric power generation and fuel cells; literature " Rae-YoungKimandJih-ShengLai.Aseamlessmodetransfermaximumpowerpointtrackingcontrollerforthermoelectricgeneratorapplications[J].IEEETransactionsonpowerelectronics, 2008, 24(5): 2310-2318."The input and output current of the buck-boost converter studied is continuous, but it contains two independent inductors. Big. At the same time, the above-mentioned buck-boost converter can only realize power conversion from a single input source to a load, and cannot simultaneously realize power conversion between multiple input sources and loads. On the other hand, the current stress of the switching tube in the boost circuit of the single-input buck-boost converter is large, which is especially not suitable for low-voltage and high-current applications.

Contents of the invention

Purpose of the invention:

Aiming at the deficiencies of the prior art, the present invention provides a parallel multi-input coupled inductance buck-boost converter.

Technical solutions:

The present invention adopts following technical scheme for realizing above-mentioned purpose of the invention:

The converter is composed of N step-up circuits, a step-down circuit (20) and a load (R _o ), where N is a natural number greater than 1, where:

Each of the N booster circuits is composed of an input source, a filter inductor, a switch tube, and a diode. The positive pole of the input source is connected to the ① end of the filter inductor, and the ② end of the filter inductor is respectively connected to the switch tube. The drain is connected to the anode of the diode, the source of the switch tube is connected to the negative pole of the input source, the cathode of the diode forms the positive output terminal of the boost circuit, and the negative pole of the input source forms the negative output terminal of the boost circuit;

The output terminals of the N booster circuits are connected in parallel with each other, and the N booster circuits share a filter capacitor (C _m ), and the two ends of the filter capacitor (C _m ) are respectively connected to the positive and negative output terminals of the N booster circuits connected.

The step-down circuit (20) is composed of a first switching tube (Q _o ), a first diode (D _o ), N filter inductors (L _o-1 , L _o-2 ... L _oN ) and a first filter capacitor (C _o ), the ① terminal of the K-th filter inductor (L _oK ) among the N filter inductors and the ② terminal of the (K+1)-th filter inductor (L _o-(K+1) ) connected to terminals, where K is a natural number less than N, the drain of the first switch (Q _o ) is connected to the positive output terminals of N booster circuits, and the source of the first switch (Q _o ) is connected to the first two The cathode of the pole tube (D _o ) is connected to the ② end of the first filter inductor (L _o-1 ), and the ① end of the Nth filter inductor (L _oN ) is respectively connected to one end of the first filter capacitor (C _o ) and the load ( One end of R _o ) is connected, and the other end of the load (R _o ) is respectively connected to the other end of the first filter capacitor (C _o ), the anode of the first diode (D _o ) and the negative output terminals of N boosters ;

Among the N step-up circuits, the filter inductance (L _iJ ) in the J-th step-up circuit and the J-th filter inductance (L _oJ ) in the step-down circuit (20) are coupled together through a magnetic core, and J is A natural number less than or equal to N, and the terminal ① of the filter inductor (L _iJ ) in the Jth step-up circuit and the terminal ① of the Jth filter inductor (L _oJ ) in the step-down circuit (20) have the same name, and the Jth Terminal ② of the filter inductor (L _iJ ) in the boost circuit and terminal ② of the Jth filter inductor (L _oJ ) in the step-down circuit (20) have the same name.

The present invention has following technical effect:

(1) Able to realize buck-boost conversion between multiple input sources and load voltages, suitable for applications where the voltage varies in a wide range;

(2) A plurality of input sources share a step-down circuit to form a load output terminal, which reduces the number of converter switch tubes and simplifies the circuit structure;

(3) The filter inductance in the boost circuit and the step-down circuit share the inductance magnetic core, which reduces the number of magnetic cores used in the converter, and can improve the dynamic performance of the converter through inductive coupling;

(4) The voltage of multiple input sources and the load voltage can be independently controlled, and the control is simple;

(5) The current at the input terminal is continuous and the pulsation is small, and multiple input sources can supply power to the load at the same time or time-sharing, which greatly increases the control strategy of the converter and makes the control diversified.

Description of drawings

Accompanying drawing 1 is the schematic diagram of the circuit structure of converter of the present invention;

Accompanying drawing 2 is the schematic diagram of the circuit structure of converter of the present invention when double input;

Accompanying drawing 3～Fig. 9 is the equivalent circuit schematic diagram of each switching mode of the converter of the present invention when double input;

Explanation of symbols in the above drawings: 1, 2, N-the number of the step-up circuit; 20-the step-down circuit; V _in1 ~V _inN -the input DC source in the 1st~N step-up circuits; L _in-1 ~L _in-1 - filter inductance in the 1st to N step-up circuits; Q ₁ to Q _N - switch tubes in the 1st to N step-up circuits; D ₁ to D _N - diodes in the 1st to N step-up circuits ; C _m - the filter capacitor of the step-up circuit; Q _o - the first switch tube in the step-down circuit; D _o - the first diode in the step-down circuit; L _o-1 ~ L _oN - the first ~ in the step-down circuit N filter inductors; C _o - filter capacitor in the step-down circuit; R _o - load; V _o - output voltage.

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

The present invention adopts the method of cascading the step-up circuit and the step-down circuit to realize the buck-boost conversion between the input source and the load voltage, so as to meet the needs of wide range variation of the input source voltage; adopts the method of parallel connection of the step-up circuit to realize power expansion , that is, the input of each step-up circuit can be the same type of input source, or a different type of input source, so as to meet the application requirements of the distributed generation system, and at the same time reduce the current stress of the switch tube in the single step-up circuit; Each boost circuit is independently controlled, reducing the difficulty of implementing each boost circuit and improving the overall efficiency of the converter; by coupling the filter inductance in the boost circuit and the step-down circuit to each other, the magnetic components in the converter are reduced The number of the converter reduces the size and weight of the converter. The coupling between the filter inductors can also cancel the high-frequency ripple in the inductor and improve the dynamic performance of the converter.

As shown in Figure 1, the converter is composed of N boost circuits, one step-down circuit (20) and a load (R _o ), where N is a natural number greater than 1, wherein: among the N boost circuits Each step-up circuit is composed of an input source, a filter inductor, a switch tube and a diode. The anode of the input source is connected to the ① terminal of the filter inductor, and the ② terminal of the filter inductor is respectively connected to the drain of the switch tube and the anode of the diode. The source of the tube is connected to the negative pole of the input source, the cathode of the diode forms the positive output terminal of the booster circuit, and the negative pole of the input source forms the negative output terminal of the booster circuit; the output terminals of the N booster circuits They are connected in parallel with each other, and the N booster circuits share a filter capacitor (C _m ), and the two ends of the filter capacitor (C _m ) are respectively connected to the positive and negative output terminals of the N booster circuits. The step-down circuit (20) is composed of a first switching tube (Q _o ), a first diode (D _o ), N filter inductors (L _o-1 , L _o-2 ... L _oN ) and a first filter capacitor (C _o ), the ① terminal of the K-th filter inductor (L _oK ) among the N filter inductors and the ② terminal of the (K+1)-th filter inductor (L _o-(K+1) ) connected to terminals, where K is a natural number less than N, the drain of the first switch (Q _o ) is connected to the positive output terminals of N booster circuits, and the source of the first switch (Q _o ) is connected to the first two The cathode of the pole tube (D _o ) is connected to the ② end of the first filter inductor (L _o-1 ), and the ① end of the Nth filter inductor (L _oN ) is respectively connected to one end of the first filter capacitor (C _o ) and the load ( One end of R _o ) is connected, and the other end of the load (R _o ) is respectively connected to the other end of the first filter capacitor (C _o ), the anode of the first diode (D _o ) and the negative output terminals of N boosters ; In the N boost circuits, the filter inductor (L _iJ ) in the J boost circuit and the J filter inductor (L _oJ ) in the step-down circuit (20) are coupled together through a magnetic core, J is a natural number less than or equal to N, and the ① end of the filter inductor (L _iJ ) in the Jth step-up circuit and the ① end of the Jth filter inductor (L _oJ ) in the step-down circuit (20) have the same name, and the Jth Terminal ② of the filter inductor (L _iJ ) in the boost circuit and terminal ② of the Jth filter inductor (L _oJ ) in the step-down circuit (20) have the same name.

Taking dual input as an example, the working principle of the converter of the present invention will be specifically analyzed in conjunction with accompanying drawings 2 to 9.

When the converter is working: Both boost circuits can work in the boost or non-boost working state. When the boost circuit works in the boost state, the switch tube in the corresponding boost circuit is in the switch state. When the circuit works in the non-boost state, the switch tube in the corresponding boost circuit remains off; the step-down circuit can work in the step-down or non-step-down working state, and when the step-down circuit works in the step-down state, the corresponding switch The tube is in the switch state, and when the step-down circuit works in the non-step-down state, the corresponding switch tube is in the always-on state.

According to the working state of the boost circuit and the step-down circuit, the converter has 8 working states.

Working state 1: The boost circuit 1 works in the boost state, the boost circuit 2 works in the boost state, and the step-down circuit works in the step-down state. At this time, the switch tubes Q ₁ , Q ₂ and Q _o in Fig. 2 Both work in the switch state.

Working state 2: The boost circuit 1 works in the boost state, the boost circuit 2 works in the boost state, and the step-down circuit works in the non-step-down state. At this time, the switch tubes Q ₁ and Q _{2 in the accompanying drawing 2} work in the In the switch state, the switch tube Q _o is always on, and the equivalent circuit is shown in Figure 3.

Working state 3: The boost circuit 1 works in the boost state, the boost circuit 2 works in the non-boost state, and the step-down circuit works in the step-down state. At this time, the switch tubes Q ₁ and Q _o in the accompanying drawing 2 work in the In the switch state, the switch tube _Q2 is always off, and the equivalent circuit is shown in Figure 4.

Working state 4: The boost circuit 1 works in the boost state, the boost circuit 2 works in the non-boost state, and the step-down circuit works in the non-buck state. At this time, the switching tube Q ₁ in the accompanying drawing 2 works in the switch state , the switching tube _Q2 is always off, and the switching tube Qo is always on. The equivalent circuit is shown in Fig. 5 .

Working state 5: The boost circuit 1 works in the non-boost state, the boost circuit 2 works in the boost state, and the step-down circuit works in the step-down state. At this time, the switch tubes Q ₂ and Q _o in the accompanying drawing 2 work in the In the switch state, the switch tube Q1 is always off, and the equivalent circuit is shown in Figure ₆ .

Working state 6: The boost circuit 1 works in the non-boost state, the boost circuit 2 works in the boost state, and the step-down circuit works in the non-buck state. At this time, the switching tube Q ₂ in the accompanying drawing 2 works in the switch state , the switching tube Q1 is always off, the switching tube Qo is always on, and the equivalent circuit is shown in _Fig . 7 .

Working state 7: The boost circuit 1 works in the non-boost state, the boost circuit 2 works in the non-boost state, and the step-down circuit works in the step-down state. At this time, the switching tube Q _o in the accompanying drawing 2 works in the switching state , the switch tubes Q ₁ and Q ₂ are always turned off, and the equivalent circuit is shown in Figure 8 .

Working state 8: The boost circuit 1 works in the non-boost state, the boost circuit 2 works in the non-boost state, and the step-down circuit works in the non-buck state. At this time, the switch tubes Q ₁ and Q 2 in the accompanying drawing ₂ is always off, and the switch tube Q _o is always on, and the equivalent circuit is shown in Fig. 9 .

From the above analysis, it can be seen that the input and output terminals of the converter can be independently controlled, and the control strategy of the converter can be selected in a variety of ways. Power can be supplied to the load through buck-boost conversion.

Claims (1)

1. a parallel multi input coupling inductance buck-boost converter, is characterized in that:

This converter is by N number of booster circuit, filter capacitor (C _m), 1 reduction voltage circuit (20) and load (R _o) composition, N be greater than 1 natural number, wherein:

Each booster circuit in described N number of booster circuit is all made up of input source, filter inductance, switching tube, diode, the positive pole of input source connects the 1. end of filter inductance, 2. the end drain electrode of connecting valve pipe and the anode of diode respectively of filter inductance, the source electrode of switching tube is connected with the negative pole of input source, the negative electrode of described diode forms the positive output end of booster circuit, and the negative pole of described input source forms the negative output terminal of booster circuit;

The output of described N number of booster circuit is connected in parallel with each other, and N number of booster circuit shares a filter capacitor (C _m), filter capacitor (C _m) two ends be connected with the positive and negative output of N number of booster circuit respectively;

Described reduction voltage circuit (20) is by the first switching tube (Q _o), the first diode (D _o), N number of filter inductance (L _o-1, L _o-2l _o-N) and the first filter capacitor (C _o) composition, K filter inductance (L in described N number of filter inductance _o-K) 1. end and (K+1) individual filter inductance (L _o-(K+1)) 2. end be connected, wherein K is the natural number being less than N, the first switching tube (Q _o) drain electrode be connected with the positive output end of N number of booster circuit, the first switching tube (Q _o) source electrode respectively with the first diode (D _o) negative electrode and the first filter inductance (L _o-1) 2. end be connected, N filter inductance (L _o-N) 1. end respectively with the first filter capacitor (C _o) one end and load (R _o) one end be connected, load (R _o) the other end respectively with the first filter capacitor (C _o) the other end, the first diode (D _o) anode and N number of booster circuit negative output terminal be connected;

In described N number of booster circuit, the filter inductance (L in J booster circuit _i-J) with reduction voltage circuit (20) in J filter inductance (L _o-J) be coupled by a magnetic core, J is the natural number being less than or equal to N, and filter inductance (L in J booster circuit _i-J) 1. end and reduction voltage circuit (20) in J filter inductance (L _o-J) 1. end be Same Name of Ends, filter inductance (L in J booster circuit _i-J) 2. end and reduction voltage circuit (20) in J filter inductance (L _o-J) 2. end be Same Name of Ends.