TW202408140A - High boost converter - Google Patents

Abstract

The invention relates to a high boost converter. It is mainly a single ended primary inductance converter (SEPIC), which is suitable for electric energy conversion of renewable energy and has the characteristics of high voltage gain, high application range, high power application, few circuit components, high conversion efficiency, etc., so as to increase the practicality and efficiency for the whole implementation.

Description

High Boost Converter(2)

The invention relates to a high-boost converter, in particular to a high-boost Sepic converter, which is suitable for use in renewable energy power systems and has high voltage gain, high application range, high power application, low circuit components, and high conversion Efficiency and other characteristics, and those that add practical functional characteristics in its overall implementation and use.

According to reports, the intensification of global warming has led to serious abnormal changes in the earth's climate. Countries around the world have begun to actively examine this serious problem. Therefore, starting from December 1997, when 38 countries and the European Union signed the "Kyoto Protocol" in Japan, the Center for Economic Cooperation and Development in 2015 At the 21st United Nations Climate Change Conference [COP 21] held in Paris, France, the historic "Paris Agreement" was adopted. 195 participating countries unanimously agreed to control greenhouse gas emissions and industrialize to prevent global warming from exceeding 2 degrees Celsius by 2100. And strive to control it within 1.5 degrees, and then to the 24th United Nations Climate Change Conference [COP 24] held in Poland in 2018, we will continue to ensure the international standards and carbon reduction goals of each country's carbon emission reduction. As solar and wind power generation technologies improve and costs gradually decrease, the development of renewable energy power generation technology and high-efficiency power conversion technology are inevitable trends in future technological development. In this way, excessive use of petrochemical energy can be avoided and carbon dioxide emissions can be reduced.

In terms of renewable energy or green energy, common ones include solar energy, tidal energy, wind energy, hydraulic energy, biomass energy, geothermal energy and fuel cells. Among these renewable energy sources, the technology of solar energy and fuel cell power generation systems is used in distributed DC It is most commonly used and discussed in power generation systems. The renewable energy distributed power generation power system includes solar components, fuel cell components, high step-up DC converter [high step-up dc-dc converter], inverter [inverter, dc-dc power converter] and load or power grid. In terms of solar power generation systems, solar arrays convert light energy into electrical energy, and each solar array can be composed of several solar modules connected in series or in parallel. However, too many solar arrays connected in series will cause lattice mismatch. Or because the shadowing effect cannot be avoided, the output voltage of the solar array is limited, which is usually lower than 50V. Therefore, the system needs a high boost converter to inject the high DC voltage of 400V as a subsequent DC-AC inverter. The high DC input voltage is then used by the inverter to output power to AC loads (such as motors) or in parallel with the mains. Therefore, high boost converters play an important role in distributed power generation systems.

In distributed power generation systems, solar power generation and fuel cells are one of the most important renewable energy sources. However, in home applications, in order to ensure the safety and reliability of the use environment, the output side of renewable energy sources generally has low DC voltage, usually low At 40V _dc , in order to meet the needs of subsequent grid-connected power generation or connection to a DC microgrid, a boost converter is first used to increase the low voltage to a high voltage DC bus, usually increasing the voltage by about 10 times to generate a frequency converter [DC-AC Inverter] required high DC voltage. For power systems that use renewable energy, for example, for a single-phase AC 220V power grid system, the high-voltage DC bus is usually 380V~400V to facilitate the load application of DC-AC back-end inverters or parallel mains use.

However, as can be seen from the above-mentioned high-voltage boost technology, although the traditional switched inductor boost technology can achieve the expected effect of simplifying the circuit and improving the voltage conversion ratio of the converter, it has also been found in its actual implementation that this technology can no longer be used. Further improve the converter boost ratio; in addition, the coupled inductor boost technology cannot have the boost function of switching inductors due to limitations of the circuit topology, so there is still room for improvement in the overall circuit design.

The reason is that, in view of this, the inventor has relied on many years of rich design, development and actual production experience in this related industry, and has further researched and improved the existing structure and deficiencies to provide a high boost converter in order to achieve better practical value. Purpose person.

The main purpose of the present invention is to provide a high-boost converter, which is mainly a high-boost Sepic converter, suitable for use in renewable energy power systems, with high voltage gain, high application range, high power application, low circuit components, and high Conversion efficiency and other characteristics, and add practical functional characteristics in its overall implementation and use.

In order to have a more complete and clear disclosure of the technical content, the purpose of the invention and the effects achieved by the present invention, they are described in detail below, and please refer to the disclosed drawings and drawing numbers:

First, please refer to the circuit diagram of the present invention shown in the first figure. The converter (1) of the present invention is mainly a high-boost Sepic converter. When the input voltage The positive electrode is connected to the primary side of the coupled inductor. The first end, the primary side of the coupled inductor A magnetized inductor is formed , the primary side of the coupled inductor The second terminals are respectively connected to the first diodes The positive electrode and the second diode the positive electrode, the first diode The negative pole is connected to the secondary side of the coupling inductor. The first end, the secondary side of the coupled inductor The second terminals are respectively connected to the second diodes Negative pole, switch The first terminal and the first capacitor the first terminal, the first capacitor The second end is connected to the first inductor respectively. The first terminal and the output diode the positive pole, the output diode The negative poles are connected to the output capacitors respectively. The first end and load the first terminal, and then let the input voltage The negative pole of the switch is connected to the The second terminal, the first inductor The second terminal, the output capacitor The second terminal and load the second end.

In the steady state, the action of the converter (1) in one switching cycle can be divided into two linear operation stages according to the switch switching and whether each diode is conductive. For the timing and waveform of the power converter, please refer to the timing diagram of the present invention in the second figure again; Assume:

1. The converter (1) has reached steady state and the operating mode is continuous conduction mode [CCM].

2. All components of this converter (1) are ideal, and the magnetic components and capacitors do not have parasitic capacitance, inductance, or resistance.

3. All the capacitors of this converter (1) are large enough, and the voltage ripple is almost 0, making the capacitor voltage a constant. Therefore, the capacitor voltage is regarded as a certain voltage source, and the output voltage Can be regarded as a constant.

4. Coupled inductor, the number of turns are and , define the turns ratio . The magnetizing inductance is much larger than the leakage inductance, and the coupling coefficient .

The first stage［ ]: [Switch ：ON, first diode :OFF, second diode ：ON, output diode :OFF]: Please refer to the third figure again as shown in the equivalent linear circuit diagram of the first stage of the present invention. This stage is , the switch The state switches from OFF to ON, the first diode , the output diode is the OFF state, the second diode When switching from OFF to ON, the magnetizing inductor Because the input voltage across Then the current has a slope rises linearly when the switch switches from ON to OFF, while the second diode Switching from ON to OFF, the first diode , the output diode When switching from OFF to ON, the converter (1) enters a switching cycle Next, the second stage circuit action.

The second stage［ ]: [Switch :OFF, first diode ：ON, second diode :OFF, output diode :ON]: Please also refer to the fourth figure for the second stage equivalent linear circuit diagram of the present invention. This stage is , the switch changes from ON to OFF, while the first diode , the output diode Switching from OFF to ON, the second diode When switching from ON to OFF, the magnetizing inductor The voltage on , then the current has a slope linear decrease; when the switch When switching from OFF to ON, the converter (1) enters the next stage and completes one cycle. The following circuit action.

According to the operating principle of the converter (1), the steady-state characteristics of the converter (1) are deduced; in order to simplify the analysis, the leakage inductance and the components on the original are ignored.

In the first stage the switch When turned on, circuit analysis can show that the primary side of the coupled inductor The magnetizing inductor Voltage and the first inductor Voltage , its voltage relationship is

(1)

In the same way, the switch can be used in the second stage When there is no conduction, circuit analysis can show that the primary side of the coupling inductor The magnetizing inductor Voltage and the first inductor Voltage , its voltage relationship is

,in (2)

Since the first inductor Voltage It must satisfy the principle of volt-second balance [principle of volt-second balance], that is, the average voltage is zero during a complete switching cycle. The formula is as follows

(3)

Organize the available output capacitor voltage with the first capacitor voltage The voltage gain is

(4)

According to the relationship between equations (1 and 2) and using the concept of the principle of volt-second balance, the magnetizing inductance can be obtained Voltage for

(5)

From the results of circuit analysis, it can be known that the output capacitor voltage with input voltage The voltage gain is

(6)

Therefore, the voltage gain M of the converter (1) is

(7)

From the second stage of the operating principle of the converter (1), the switch can be obtained voltage stress

(8)

On the other hand, the first diode can be obtained from the first stage and the output diode voltage stress

(9)

In the second stage, the second diode can be found voltage stress

(10)

From equation (7), it can be seen that the voltage gain of the converter (1) has two degrees of design freedom: coupled inductor turns ratio and conduction ratio ; The converter (1) can achieve a high boost ratio by appropriately designing the turns ratio of the coupling inductor without having to operate at a very large conduction ratio. Corresponding to different coupled inductor turns ratios and conduction ratio The voltage gain curve of , When, the voltage gain is 5 times; when the conduction ratio , When , the voltage gain is 13.3 times.

In addition, based on the circuit action analysis results, use Is-Spice software to perform preliminary simulations (please refer to the sixth figure again for the schematic diagram of the analog circuit of the present invention) to verify the converter (1) analysis results and the accuracy of the component waveforms. The electrical specifications are shown in Table 1 below. input voltage 40 V conduction ratio 0.738 Output voltage 200V Magnetizing inductance 500μH Output power 500W first inductor 1.6mH switching frequency 100kHz Output capacitor 470μF Table 1 Electrical specifications and component parameters

The simulation results are as follows:

1. Electrical specification verification: switch drive signal , switch cross voltage , input voltage , output voltage :

Please refer to Figure 7 again for the switch driving signal of the present invention. , switch cross voltage , input voltage , output voltage As shown in the simulation waveform diagram, when the conduction ratio When, the input voltage , the output voltage can be obtained , to meet the electrical requirements and specifications.

2. Electrical specification verification: switch drive signal , magnetizing inductor voltage , magnetizing inductor current :

Please refer to Figure 8 again for the switch driving signal of the present invention. , magnetizing inductor voltage , magnetizing inductor current As shown in the simulation waveform diagram, the average magnetizing inductor voltage is zero, consistent with the viewpoint of volt-second balance. In addition, the magnetizing inductor current The minimum value is greater than zero, which indicates that the converter (1) operates in continuous conduction mode [Continuous Conduction Mode, CCM].

3. Electrical specification verification: switch drive signal , the first inductor voltage , the first inductor current :

Please refer to Figure 9 again for the switch driving signal of the present invention. , the first inductor voltage , the first inductor current As shown in the simulation waveform diagram, the average first inductor voltage is zero, consistent with the volt-second balance point of view, in addition, the first inductor current The minimum value is greater than zero, which indicates that the converter (1) operates in continuous conduction mode [Continuous Conduction Mode, CCM].

From the above and the description of the use of the present invention, it can be seen that compared with the existing technical means, the present invention is mainly a high-boost Sepic converter, which is suitable for use in renewable energy power systems and has the following advantages:

1. High voltage gain: The converter introduces coupled inductor boost technology, which can freely adjust the coupled inductor turns ratio and switch conduction ratio to improve the voltage gain characteristics without operating at a huge conduction ratio.

2. High application range: The converter has no conduction ratio limit and has a large working application range.

3. High-power applications: It can be applied to any boost converter to achieve high-power performance.

4. Low circuit components: Taking the traditional Sepic converter as an example, it only needs to add a set of coupling inductors and two diodes, which is higher than the traditional Sepic converter. times, it can also achieve high voltage gain characteristics, and requires fewer circuit components, which can reduce circuit costs.

5. High conversion efficiency: The number of components in the converter is small, so the losses on the components can be greatly reduced, which can improve the overall conversion efficiency of the converter.

However, the foregoing embodiments or drawings do not limit the product structure or usage of the present invention. Any appropriate changes or modifications made by those with ordinary knowledge in the technical field shall be regarded as not departing from the patent scope of the present invention.

In summary, the embodiments of the present invention can indeed achieve the expected use effects, and the specific structure disclosed has not only been seen in similar products, but has also not been disclosed before the application, and it fully complies with the provisions of the patent law. If you submit an application for an invention patent in accordance with the law, please review it and grant a patent, it will be very convenient.

1: Converter

:Input voltage

:Primary side of coupled inductor

:Magnetizing inductor

:Secondary side of coupled inductor

:First diode

:Second diode

:Output diode

:switch

:First capacitor

:Output capacitor

:First inductor

:load

Figure 1: Circuit diagram of the present invention

The second figure: timing diagram of the present invention

Figure 3: Equivalent linear circuit diagram of the first stage of the present invention

Figure 4: Equivalent linear circuit diagram of the second stage of the present invention

Figure 5: Graph of voltage gain versus conduction ratio and coupled inductor turns ratio of the present invention

Figure 6: Schematic diagram of the analog circuit of the present invention

Figure 7: Switch driving signal of the present invention , switch cross voltage , input voltage , output voltage Analog waveform diagram

Figure 8: Switch driving signal of the present invention , magnetizing inductor voltage , magnetizing inductor current Analog waveform diagram

Figure 9: Switch driving signal of the present invention , the first inductor voltage , the first inductor current Analog waveform diagram

1: Converter

V _in : input voltage

N _{p 1} : primary side of coupled inductor

L _m :magnetizing inductance

N _{s 1} : secondary side of coupled inductor

D ₁ : first diode

D ₂ : Second diode

D _o :Output diode

SW : switch

C ₁ : first capacitor

C _o : output capacitor

L ₁ : first inductor

R : load

Claims (3)

A high-boost converter, which mainly connects the positive electrode of the input voltage to the first end of the primary side of the coupling inductor, and the second end of the primary side of the coupling inductor is connected to the anode of the first diode and the second end of the second diode respectively. The positive electrode of the polar body, the negative electrode of the first diode is connected to the first end of the secondary side of the coupling inductor, and the second end of the secondary side of the coupling inductor is connected to the negative electrode of the second diode and the first end of the switch respectively. and the first end of the first capacitor, the second end of the first capacitor is connected to the first end of the first inductor and the positive electrode of the output diode, and the negative electrode of the output diode is connected to the first end of the output capacitor and The first terminal of the load is connected to the negative terminal of the input voltage to the second terminal of the switch, the second terminal of the first inductor, the second terminal of the output capacitor and the second terminal of the load respectively. The high-boost converter according to claim 1, wherein the converter has a magnetizing inductor formed on the primary side of the coupling inductor. The high boost converter of claim 1, wherein the voltage gain of the converter is , where D is the conduction ratio.

Images