CN104184322B - A kind of converter of symmetrical structure - Google Patents

Abstract

The invention discloses a converter device with a symmetrical structure, which includes: 2 input power sources V1, V2, 1 input capacitor C1 and an adjustable voltage Uc generated at both ends thereof, and 1 output capacitor C2 generated output at both ends Voltage Vo, 2 energy storage inductances L1, L2 and 3 switch tubes, the DC converter generates a regulated voltage Uc on the input capacitor C1 by turning on and off the first to third switch tubes, and the The regulated voltage Uc works together with the input current I ₁ generated by the input power supply V1 and the input current I ₂ generated by the input voltage V2 to generate the output current I _C to the output capacitor C2, and different switch combinations can increase or decrease the output current I _C Small. The input current and output voltage ripples of the DC converter of the present invention are small, which is beneficial to prolong the service life of the input power supply, has a simple structure, requires fewer switching devices, has small loss, and has high efficiency, which can effectively improve the efficiency of the converter. performance and cost reduction, and the output current is controllable.

Description

A Transformer with a Symmetrical Structure

technical field

The invention relates to a converter, especially a DC converter with a symmetrical structure.

Background technique

In recent years, energy shortage and environmental pollution have become the focus of the world, and the development and application of renewable energy have attracted widespread attention from all over the world. In the renewable energy power generation system, the electric energy generated by many renewable energy sources is low-voltage direct current, and high-voltage direct current is required for power transmission to the grid, so a DC-DC converter is required to convert the low-voltage direct current into suitable and high voltage direct current from the network. In the field of clean energy electric vehicles, it is often necessary to convert the low-voltage single direct current provided by the battery into high-voltage direct current of different voltage values, which has high requirements on the efficiency of DC-DC conversion and the stability of the output DC voltage . Therefore, converters with low output voltage ripple, high gain, and high efficiency play a very important role in the application fields of renewable energy grid-connected power generation and clean energy electric vehicles. In order to boost the voltage of the photovoltaic or fuel cell array to the DC bus voltage required by the grid-connected inverter, the photovoltaic or fuel cell array is usually connected in series, and then boosted by a BOOST or two-phase interleaved parallel BOOST circuit. The boost ratio of the converter is equal. When the input voltage is low, in order to achieve a higher output voltage, the switch on-duty ratio will be close to 1, which will reduce the efficiency of the converter on the one hand, and at the same time the switching frequency It is not easy to improve further. In order to achieve a higher step-up ratio, some literature also proposed to directly cascade two BOOST converters as a front-end converter, which increases the number of stages of the system and the complexity of control, which is not conducive to the improvement of system efficiency and performance. Therefore, it is of great theoretical significance and application value to study a new high-performance DC-DC converter with a larger boost ratio to meet the needs of the subsequent grid-connected inverter.

As disclosed in the public document (CN102223068B), a combined DC-DC converter includes two DC input power sources (Vin1, Vin2) (1), which can be photovoltaic cells or fuel cells, and two completely symmetrical boost converters Modules ② and ③) are composed. The boost converter module ② consists of two boost inductors (L1, L3), two power switch tubes (Q1, Q3), four unidirectional rectifier diodes (D1~D4), and two intermediate energy storage capacitors (C1, C3), an output filter capacitor (Co1); the boost converter module ③ consists of two boost inductors (L2, L4), two power switch tubes (Q2, Q4), four unidirectional rectifier diodes (D5～ D8), two intermediate energy storage capacitors (C2, C4), and an output filter capacitor (Co2). Consider Q1 and Q2 as a group of synchronous switches, which are driven by the same drive signal 1, and Q3 and Q4 are a group of synchronous switches, which are driven by one drive signal 2; the two groups of switch tubes are controlled by the method of complementary drive signals. However, its structure and control are complex, many switching devices are required, and the output current cannot be adjusted, resulting in high cost of the converter, which is not conducive to popularization and application.

Contents of the invention

The object of the present invention is to address the shortcomings of the converter structure in the prior art, and propose a symmetrical DC converter with a simple structure and fewer switching devices, which has low loss and high converter conversion efficiency.

The DC converter with a symmetrical structure of the present invention includes: 2 input power sources V1, V2, 1 input capacitor C1 and an adjustable voltage Uc generated at both ends thereof, 1 output capacitor C2 and an output voltage Vo generated at its two ends, 2 An energy storage inductor L1, L2 and three switch tubes are arranged in a symmetrical structure. The specific topology is: the negative pole of the input power supply V1 is connected to the lower end of the input capacitor C1, and the positive pole of the input power supply V1 is connected to one end of the first switch tube S1. The positive pole of the input power supply V2 is connected to the upper end of the input capacitor C1, the upper end of the input capacitor C1 is connected to one end of the first energy storage inductor L1, the lower end of the input capacitor C1 is connected to one end of the second energy storage inductor L2, and the other end of the first energy storage inductor L1 One end is connected to the other end of the first switch tube S1, and the connection point is connected to one end of the second switch tube S2, the other end of the second energy storage inductance L2 is connected to the other end of the second switch tube S2, and the connection point is connected to the third One end of the switch tube S3, the other end of the third switch tube S3 is connected to the negative pole of the input power supply V2, the positive terminal of the output capacitor C2 is connected to the positive pole of the input power supply V1, the negative terminal of the output capacitor C2 is connected to the negative pole of the input power supply V2, the first to the second The three switching tubes all have anti-parallel diodes, and the DC converter generates the regulated voltage Uc on the input capacitor C1 through the switching on and off of the first to third switching tubes, and the regulated voltage Uc and the input power supply V1 generate The input current I1 of the input current _I1 and the input current _I2 generated by the input voltage V2 work together to generate the output current I _C to the output capacitor C2, and different switch combinations can increase or decrease the output current I _C.

When the adjusted voltage Uc is positive at the top and negative at the bottom, the second switching tube S2 is turned on, the first switching tube S1 and the third switching tube S3 are turned off, and the input capacitor C1, the first energy storage inductor L1, and the second energy storage inductor L2 A circulating current is formed, and a first energy storage current I _L1 is generated on the first energy storage inductor L1 , and a second energy storage current I L2 is generated on the second energy storage inductor _L2 . When the second switch tube S2 is turned off, the first switch tube S1 and the third switch tube S3 are turned on, and the energy storage current I _L1 and I _L2 stored in the first energy storage inductance and the second energy storage inductance pass through The first switching tube S1 and the third switching tube S3 flow to the output capacitor C2, at the same time, the input current _I1 and the input current _I2 also directly flow from the input power supply V1, V2 to the output capacitor C2 to achieve the purpose of output voltage, at this time The amount of current _IC flowing to the output capacitor will increase accordingly due to the shunting of I _L1 and I _L2 .

When the regulated voltage Uc is up negative and down positive, the first switching tube S1 and the third switching tube S3 are turned on, and the second switching tube S2 is turned off. Under the action of V2 and input capacitor C1, the opposite first energy storage current I _L1 will be generated on the first energy storage inductor L1 and the opposite second energy storage current I _L2 will be generated on the second energy storage inductor L2, and stored in In the energy storage inductors L1 and L2, next, the first switch tube S1 and the third switch tube S3 are turned off, and when the second switch tube S2 is turned on, the first energy storage current I _L1 and the second energy storage inductor L2 The energy storage current I _L1 and I _L2 stored in the second switch tube S2 flow to the input capacitor C1, at the same time, the input current I ₁ and the input current I ₂ directly flow from the input power supply V1, V2 to the output capacitor C2, reaching the output voltage For the purpose, the amount of current _IC flowing to the output capacitor will be reduced accordingly due to the shunting of I _L1 and I _L2 .

The first to third switching tubes may be high-power switching devices such as IGBT or MOSFET. The input power sources V1 and V2 are both new energy storage power sources such as storage batteries, fuel cells or photovoltaic cells, or the input power sources V1 are storage batteries and the input power sources V2 are photovoltaic cells, or the input power sources V1 and V2 are storage batteries, fuel cells, etc. A combination of any two of the three types of batteries or photovoltaic cells.

The input current and output voltage ripples of the DC converter of the present invention are small, which is beneficial to prolong the service life of the input power supply, has a simple structure, requires fewer switching devices, has small loss, and has high efficiency, which can effectively improve the efficiency of the converter. performance and cost reduction, and the output current is controllable.

Description of drawings

Figure 1: Topological structure diagram of an existing symmetrical converter;

Fig. 2: Topological structure diagram of a DC converter with a symmetrical structure in the present invention.

detailed description

It can be seen from FIG. 2 that the DC converter of the present application includes two input power sources V1 and V2, one input capacitor C1 and an adjustable voltage Uc at both ends thereof, and one output capacitor C2 and an output voltage Vo at both ends thereof. 2 energy storage inductors L1, L2 and 3 switching tubes, which are arranged in a symmetrical structure. The specific topology is: the negative pole of the input power supply V1 is connected to the lower end of the input capacitor C1, and the positive pole of the input power supply V1 is connected to one end of the first switching tube S1 , the positive pole of the input power supply V2 is connected to the upper end of the input capacitor C1, the upper end of the input capacitor C1 is connected to one end of the first energy storage inductor L1, the lower end of the input capacitor C1 is connected to one end of the second energy storage inductor L2, the first energy storage inductor L1 The other end is connected to the other end of the first switch tube S1, and the connection point is connected to one end of the second switch tube S2, and the other end of the second energy storage inductance L2 is connected to the other end of the second switch tube S2, and the connection point is connected to the second switch tube S2. One end of the three-switch tube S3, the other end of the third switch tube S3 is connected to the negative pole of the input power supply V2, the positive terminal of the output capacitor C2 is connected to the positive pole of the input power supply V1, and the negative terminal of the output capacitor C2 is connected to the negative pole of the input power supply V2. The third switching tubes all have anti-parallel diodes, and the first to third switching tubes can be high-power switching devices such as IGBTs or MOSFETs. The input power sources V1 and V2 are new energy storage power sources such as batteries, fuel cells or photovoltaic cells.

The DC converter of the present application can adjust the voltage Uc generated on the input capacitor C1 by turning on and off the first to third switching tubes, and cooperate with the input current _I1 generated by the input power supply V1 and the input voltage V2 to generate The current _I2 is output to the output capacitor C2.

When the adjusted voltage Uc is positive at the top and negative at the bottom, the second switching tube S2 is turned on, the first switching tube S1 and the third switching tube S3 are turned off, and the input capacitor C1, the first energy storage inductor L1, and the second energy storage inductor L2 A circulating current is formed, and a first energy storage current I _L1 is generated on the first energy storage inductor L1 , and a second energy storage current I L2 is generated on the second energy storage inductor _L2 . When the second switch tube S2 is turned off, the first switch tube S1 and the third switch tube S3 are turned on, and the energy storage current I _L1 and I _L2 stored in the first energy storage inductance and the second energy storage inductance pass through The second switching tube S2 and the third switching tube S3 flow to the output capacitor C2. At the same time, the input current _I1 and the input current _I2 also directly flow from the input power supply V1, V2 to the output capacitor C2 to achieve the purpose of output voltage. At this time The amount of current _IC flowing to the output capacitor will increase accordingly due to the shunting of I _L1 and I _L2 .

When the regulated voltage Uc is up negative and down positive, the first switching tube S1 and the third switching tube S3 are turned on, and the second switching tube S2 is turned off. Under the action of V2 and input capacitor C1, the opposite first energy storage current I _L1 will be generated on the first energy storage inductor L1 and the opposite second energy storage current I _L2 will be generated on the second energy storage inductor L2, and stored in In the energy storage inductors L1 and L2, next, the first switch tube S1 and the third switch tube S3 are turned off, and when the second switch tube S2 is turned on, the first energy storage current I _L1 and the second energy storage inductor L2 The energy storage current I _L1 and I _L2 stored in the second switch tube S2 flow to the input capacitor C1, at the same time, the input current I ₁ and the input current I ₂ directly flow from the input power supply V1, V2 to the output capacitor C2, reaching the output voltage For the purpose, the amount of current _IC flowing to the output capacitor will be reduced accordingly due to the shunting of I _L1 and I _L2 .

The first to third switching tubes may be high-power switching devices such as IGBT or MOSFET. The input power sources V1 and V2 are both new energy storage power sources such as storage batteries, fuel cells or photovoltaic cells, or the input power sources V1 are storage batteries and the input power sources V2 are photovoltaic cells, or the input power sources V1 and V2 are storage batteries, fuel cells, etc. A combination of any two of the three types of batteries or photovoltaic cells.

Claims (5)

1. the DC converter of a symmetrical structure, comprise input power V1, V2, input capacitance C1 also produces regulation voltage Uc at its two ends, output capacitance C2 also produces output voltage Vo at its two ends, energy storage inductor L1, L2 and first ~ the 3rd switching tube S1, S2, S3, this DC converter adopts symmetrical structure to arrange, concrete topological structure is: the negative pole of input power V1 connects the lower end of input capacitance C1, the positive pole of input power V1 connects one end of the first switching tube S1, the positive pole of input power V2 connects the upper end of input capacitance C1, the upper end of input capacitance C1 connects one end of the first energy storage inductor L1, the lower end of input capacitance C1 connects one end of the second energy storage inductor L2, the other end of the first energy storage inductor L1 connects the other end of the first switching tube S1, and this tie point connects one end of second switch pipe S2, the other end of the second energy storage inductor L2 connects the other end of second switch pipe S2, and this tie point connects one end of the 3rd switching tube S3, the other end of the 3rd switching tube S3 connects the negative pole of input power V2, output capacitance C2 anode connects the positive pole of input power V1, the negative terminal of output capacitance C2 connects the negative pole of input power V2, first ~ three switching tube all has anti-paralleled diode, this DC converter is turned on and off by the first ~ three switching tube, the regulation voltage Uc that input capacitance C1 produces, and the input current I that described regulation voltage Uc and input power V1 produces ₁with the input current I that input voltage V2 produces ₂acting in conjunction produces output current I _cto output capacitance C2, and different switch combinations can make output current I _cincrease or reduce.

2. the DC converter of symmetrical structure according to claim 1, described first ~ three switching tube is IGBT or MOSFET.

3. the DC converter of symmetrical structure according to claim 1, described input power V1, V2 are all the one in storage battery, fuel cell or photovoltaic cell.

4. the DC converter of symmetrical structure according to claim 1, described input power V1 is storage battery, input power V2 is photovoltaic cell.

5. the DC converter of symmetrical structure according to claim 1, described input power V1, V2 are respectively the combination of any two kinds in storage battery, fuel cell or photovoltaic cell three kinds.