Novel MPPT circuit

Abstract

The utility model provides a novel MPPT circuit which comprises an input capacitor C1, an output capacitor C2, switch tubes Q1, Q2, Q3 and Q4, a power inductor L1 and a master control MCU, and the master control MCU is respectively connected with the switch tubes Q1, Q2, Q3 and Q4. According to the utility model, a four-tube synchronous boost-buck circuit topology is used, four switch tubes are controlled by the MCU to work so as to realize photovoltaic input maximum power tracking, and wide voltage input and wide voltage output can be realized by using four-tube synchronous boost-buck, so that various different photovoltaic input voltages and different batteries can be compatible, the environmental adaptability is strong, and the application scene is wide.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, in particular to a novel MPPT circuit. Background Art

[0002] As society continues to develop, energy demand is growing. Against the backdrop of global climate change and environmental issues, photovoltaic power generation, as a clean and renewable energy source, has broad development space. How to use solar energy as efficiently as possible is the focus of research. Many MPPTs now use boost circuits or buck circuits, which have high requirements for the photovoltaic input voltage range and can only work in a smaller voltage range. They are not well compatible with various photovoltaic voltages and cannot efficiently use solar energy. Utility Model Content

[0003] In view of the deficiencies in the prior art, the utility model proposes an MPPT circuit with a wide voltage range input and a wide voltage range output.

[0004] In order to realize the above technical scheme, the utility model provides a novel MPPT circuit, including: an input capacitor C1, an output capacitor C2, switch tubes Q1, Q2, Q3, Q4, a power inductor L1 and a main control MCU, wherein the positive electrode of the output capacitor C2 is connected to the positive electrode BAT+ of the battery, the negative electrode of the output capacitor C2 is connected to the negative electrode BAT- of the battery, the positive electrode of the input capacitor C1 is connected to the positive electrode PV+ of the photovoltaic input terminal, the negative electrode of the input capacitor C1 is connected to the negative electrode PV- of the photovoltaic input terminal, the positive electrode of the output capacitor C2 is connected to the positive electrode of the input capacitor C1, the negative electrode of the output capacitor C2 is connected to the negative electrode of the input capacitor C1, the 1st pin of the switch tube Q1 is connected to the main control MCU, and the 2nd pin of the switch tube Q1 is connected to the connection line between the positive electrode of the output capacitor C2 and the positive electrode of the input capacitor C1 , pin 3 of the switch tube Q1 is connected to pin 2 of the switch tube Q3, pin 1 of the switch tube Q3 is connected to the main control MCU, pin 3 of the switch tube Q3 is connected to the connecting line between the negative electrode of the output capacitor C2 and the negative electrode of the input capacitor C1, pin 1 of the switch tube Q2 is connected to the main control MCU, pin 2 of the switch tube Q2 is connected to the connecting line between the positive electrode of the output capacitor C2 and the positive electrode of the input capacitor C1, pin 3 of the switch tube Q2 is connected to pin 2 of the switch tube Q4, pin 1 of the switch tube Q4 is connected to the main control MCU, pin 3 of the switch tube Q4 is connected to the connecting line between the negative electrode of the output capacitor C2 and the negative electrode of the input capacitor C1, pin 1 of the power inductor L1 is connected to the connecting line between pin 3 of the switch tube Q2 and pin 2 of the switch tube Q4, and pin 2 of the power inductor L1 is connected to the connecting line between pin 3 of the switch tube Q1 and pin 2 of the switch tube Q3.

[0005] In the above technical solution, PV+ and PV- are connected to the positive and negative poles of the photovoltaic input terminal, and BAT+ and BAT- are connected to the positive and negative poles of the battery. In actual operation:

[0006] (1) When the PV input voltage is less than the battery voltage, the circuit operates in the boost mode. The switch Q1 is always on, the switch Q3 is always off, and the switch Q4 acts as a high-frequency switch to store energy in the inductor L1. The switch Q2 acts as a freewheeling diode, and Q2 and Q4 conduct complementarily to achieve the boost function. The main control MCU adjusts the duty cycles of Q2 and Q4 to track the maximum power point of the PV input.

[0007] (2) When the input PV voltage is greater than the battery voltage, the circuit operates in the buck mode. The switch Q2 is always on, the switch Q4 is always off, and the switch Q1 acts as a high-frequency switch to store energy in the inductor L1. The switch Q3 acts as a freewheeling diode, and Q1 and Q3 conduct complementarily to achieve the buck function. The main control MCU adjusts the duty cycles of Q1 and Q3 to track the maximum power point of the PV input.

[0008] (3) When the input PV voltage is close to the battery voltage, the circuit operates in the hybrid mode. The main control MCU switches between the boost mode and the buck mode according to the current demand to track the maximum power point of the PV input.

[0009] The beneficial effects of a novel MPPT circuit provided by the present utility model are as follows: The novel MPPT circuit has a simple structure and reasonable design. It can automatically compare the input PV voltage with the battery voltage and adjust the working mode automatically to achieve automatic buck or boost. Compared with a single boost circuit or a single buck circuit, the working range of the input PV voltage can be wider, and similarly, the output battery voltage can also be wider. Moreover, the present utility model uses a four-switch synchronous buck-boost circuit topology to achieve the maximum power tracking of the PV input by controlling the operation of four switches through the MCU. Because the four-switch synchronous buck-boost can achieve wide voltage input and wide voltage output, it can be compatible with various different PV input voltages, different batteries, has strong environmental adaptability, and a wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is the circuit diagram of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0012] Embodiment: A novel MPPT circuit.

[0013] Refer to Figure 1As shown in the figure, a new type of MPPT circuit includes: an input capacitor C1, an output capacitor C2, switching transistors Q1, Q2, Q3, Q4, a power inductor L1, and a main control MCU. Among them, the positive electrode of the output capacitor C2 is connected to the positive electrode BAT+ of the battery, the negative electrode of the output capacitor C2 is connected to the negative electrode BAT- of the battery, the positive electrode of the input capacitor C1 is connected to the positive electrode PV+ of the photovoltaic input terminal, the negative electrode of the input capacitor C1 is connected to the negative electrode PV- of the photovoltaic input terminal, the positive electrode of the output capacitor C2 is connected to the positive electrode of the input capacitor C1, the negative electrode of the output capacitor C2 is connected to the negative electrode of the input capacitor C1, the pin 1 of the switching transistor Q1 is connected to the main control MCU, the pin 2 of the switching transistor Q1 is connected to the wire connecting the positive electrodes of the output capacitor C2 and the input capacitor C1, the pin 3 of the switching transistor Q1 is connected to the pin 2 of the switching transistor Q3, the pin 1 of the switching transistor Q3 is connected to the main control MCU, the pin 3 of the switching transistor Q3 is connected to the wire connecting the negative electrodes of the output capacitor C2 and the input capacitor C1, the pin 1 of the switching transistor Q2 is connected to the main control MCU, the pin 2 of the switching transistor Q2 is connected to the wire connecting the positive electrodes of the output capacitor C2 and the input capacitor C1, the pin 3 of the switching transistor Q2 is connected to the pin 2 of the switching transistor Q4, the pin 1 of the switching transistor Q4 is connected to the main control MCU, the pin 3 of the switching transistor Q4 is connected to the wire connecting the negative electrodes of the output capacitor C2 and the input capacitor C1, the pin 1 of the power inductor L1 is connected to the wire connecting the pin 3 of the switching transistor Q2 and the pin 2 of the switching transistor Q4, and the pin 2 of the power inductor L1 is connected to the wire connecting the pin 3 of the switching transistor Q1 and the pin 2 of the switching transistor Q3.

[0014] The working principle of the present utility model is as follows:

[0015] Referring to Figure 1 the circuit diagram shown, PV+ and PV- are connected to the positive and negative electrodes of the photovoltaic input terminal, and BAT+ and BAT- are connected to the positive and negative electrodes of the battery.

[0016] When the input PV voltage is less than the battery voltage, the circuit operates in the boost mode. The switching transistor Q1 is always on, the switching transistor Q3 is always off, the switching transistor Q4 acts as a high-frequency switch to store energy in the inductor L1, and the switching transistor Q2 acts as a freewheeling diode. Q2 and Q4 conduct complementary to achieve the boost function. The main control MCU adjusts the duty cycles of Q2 and Q4 to track the maximum power point of the photovoltaic input.

[0017] When the input PV voltage is greater than the battery voltage, the circuit operates in the buck mode. The switching transistor Q2 is always on, the switching transistor Q4 is always off, the switching transistor Q1 acts as a high-frequency switch to store energy in the inductor L1, and the switching transistor Q3 acts as a freewheeling diode. Q1 and Q3 conduct complementary to achieve the buck function. The main control MCU adjusts the duty cycles of Q1 and Q3 to track the maximum power point of the photovoltaic input.

[0018] When the input PV voltage is close to the battery voltage, the circuit operates in a hybrid mode. The main control MCU switches between the boost mode and the buck mode according to the current demand to track the maximum power point of the PV input.

[0019] This utility model uses a four-switch synchronous buck-boost circuit topology. The MCU controls the operation of four switching tubes to achieve maximum power tracking of the PV input. Since the four-switch synchronous buck-boost can achieve wide voltage input and wide voltage output, it can be compatible with various different PV input voltages and different batteries, with strong environmental adaptability and wide application scenarios.

[0020] The novel MPPT circuit provided by this utility model can automatically compare the input PV voltage with the battery voltage and adjust the working mode by itself to achieve automatic bucking or boosting. Compared with a single boost circuit or a single buck circuit, the working range of the input PV voltage can be wider, and similarly, the output battery voltage can also be wider. The products designed with the circuit of this utility model can use different PV panels and battery panels, with good environmental adaptability.

[0021] To achieve an MPPT circuit with wide voltage range input and wide voltage range output, there are methods in the market that first step down and then step up or first step up and then step down. These two methods will have at least one more inductor compared with this utility model, resulting in higher costs. At the same time, due to the use of a two-stage circuit topology, the conversion efficiency is lower, the heat generation increases, and more costs are required to solve the heat dissipation problem, which is not environmentally friendly.

[0022] The main control of this utility model uses an MCU, which can flexibly adjust functional requirements and perform customized functions. At the same time, some additional modules or circuits can be added to achieve functions such as remote monitoring.

[0023] In practical applications, when collecting PV energy, in many cases, the energy collected by the PV device needs to be used. At this time, the energy in the battery needs to be used or converted through other devices. In addition to collecting PV energy into the battery, this utility model can also convert the battery energy to the electrical equipment. At this time, PV+ and PV- are connected to the positive and negative poles of the electrical equipment. The main control MCU works in the buck mode or the boost mode in reverse according to the voltage required by the electrical equipment compared with the battery voltage. If the circuit needs to work in the boost mode, at this time, the switching tube Q2 is always open, the switching tube Q4 is always closed, the switching tube Q3 acts as a high-frequency switch to store energy in the inductor L1, the switching tube Q1 acts as a freewheeling diode, and Q3 and Q4 are complementary to conduct to achieve the boost function. If the circuit needs to work in the buck mode, at this time, the switching tube Q1 is always open, the switching tube Q3 is always closed, the switching tube Q2 acts as a high-frequency switch to store energy in the inductor L1, the switching tube Q4 acts as a freewheeling diode, and Q2 and Q4 are complementary to conduct to achieve the buck function. Energy collection and release can be achieved through this utility model, and one circuit realizes two functions.

[0024] The above is the preferred embodiment of the present utility model, but the present utility model should not be limited to the content disclosed in this embodiment and the drawings. Therefore, all equivalent or modified implementations completed without departing from the spirit disclosed by the present utility model fall within the protection scope of the present utility model.

Claims

1. A novel MPPT circuit, characterized in that Including: Input capacitor C1, output capacitor C2, switching transistors Q1, Q2, Q3, Q4, power inductor L1, and main control MCU. Among them, the positive electrode of output capacitor C2 is connected to the positive electrode BAT+ of the battery, the negative electrode of output capacitor C2 is connected to the negative electrode BAT- of the battery, the positive electrode of input capacitor C1 is connected to the positive electrode PV+ of the photovoltaic input terminal, the negative electrode of input capacitor C1 is connected to the negative electrode PV- of the photovoltaic input terminal, the positive electrode of output capacitor C2 is connected to the positive electrode of input capacitor C1, the negative electrode of output capacitor C2 is connected to the negative electrode of input capacitor C1, pin 1 of switching transistor Q1 is connected to the main control MCU, pin 2 of switching transistor Q1 is connected to the connection line between the positive electrodes of output capacitor C2 and input capacitor C1, pin 3 of switching transistor Q1 is connected to pin 2 of switching transistor Q3, pin 1 of switching transistor Q3 is connected to the main control MCU, pin 3 of switching transistor Q3 is connected to the connection line between the negative electrodes of output capacitor C2 and input capacitor C1, pin 1 of switching transistor Q2 is connected to the main control MCU, pin 2 of switching transistor Q2 is connected to the connection line between the positive electrodes of output capacitor C2 and input capacitor C1, pin 3 of switching transistor Q2 is connected to pin 2 of switching transistor Q4, pin 1 of switching transistor Q4 is connected to the main control MCU, pin 3 of switching transistor Q4 is connected to the connection line between the negative electrodes of output capacitor C2 and input capacitor C1, pin 1 of power inductor L1 is connected to the connection line between pin 3 of switching transistor Q2 and pin 2 of switching transistor Q4, and pin 2 of power inductor L1 is connected to the connection line between pin 3 of switching transistor Q1 and pin 2 of switching transistor Q3.

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