Converter bidirectional control circuit and driving method thereof

Abstract

The invention relates to a converter bidirectional control circuit and a driving method thereof. The converter bidirectional control circuit comprises a controller, a first driving circuit, a second driving circuit, a bidirectional conversion circuit and a solar conversion circuit, the bidirectional conversion circuit comprises a plurality of switch elements, an inductance element and an energy storage element, the plurality of switch elements are divided into two groups which are connected in series, a connection point is formed between the adjacent switch elements which are connected in series, and an H bridge is formed by connecting the inductance element with a connection point formed between the adjacent switch elements which are connected in series in the other group; energy storage elements are connected in parallel to the head and tail of two groups of series-connected switch elements on the left and right sides of the H bridge; the solar conversion circuit is connected with the controller, and the sampling voltage is used for the controller to generate a control signal and adjust the output power. The controller sends out first and second control signals which are respectively converted into driving signals by the first and second driving circuits so as to control the on-off of the upper and lower end switch elements of the H bridge. The bidirectional conversion circuit stores the voltage of the solar conversion circuit in the inductor and outputs the voltage to the load through the on-off of the switching element according to the driving signal.

Description

Technical Field

[0001] The present disclosure relates to the technical field of DC-DC converters, and in particular to a converter bidirectional control circuit and a driving method thereof. Background Art

[0002] With the continuous growth of energy demand and the improvement of environmental protection awareness, efficient energy conversion technology has become a hot topic in engineering research. High-efficiency, high-power-density bidirectional converters can significantly improve power conversion efficiency, recover energy, and thus reduce energy loss. Efficient energy conversion is essential for extending battery life, improving system efficiency, recovering energy, and reducing energy costs. Non-isolated, high-efficiency, high-power-density bidirectional converters can achieve more sustainable energy utilization and more environmentally friendly energy systems. Non-isolated, high-power-density bidirectional converters can achieve more compact and lightweight electronic equipment designs.

[0003] With the popularity of wireless communications, mobile computing, and portable electronic devices, the demand for smaller and lighter power modules is increasing. By increasing the power density of non-isolated bidirectional converters, higher power output can be achieved in a limited space, thus meeting the demand for miniaturization of electronic devices. Non-isolated, efficient, and high-power-density bidirectional converters can also help promote the development and advancement of power electronics technology. By studying and designing innovative non-isolated bidirectional converter topologies, control strategies, and circuit design methods, the performance of power electronic devices and systems can be improved. This is of great significance to both academic research and engineering practice in the field of power electronics.

[0004] In relevant scenarios, the control strategies for DC-DC non-isolated bidirectional converters mainly include traditional PI control, model predictive control, sliding mode control, direct power control and other methods, or algorithms based on model predictive control, observer-based algorithms, etc., to improve energy conversion efficiency and response speed, so as to achieve efficient and stable energy conversion. The topology of DC-DC non-isolated bidirectional converters mainly adopts full-bridge topology, half-bridge topology, three-level topology, etc., or integrates DC-DC non-isolated bidirectional converters with other power electronic devices to improve conversion efficiency and reduce volume and weight. In the selection of switching devices for DC-DC non-isolated bidirectional converters, silicon-based power switching devices, silicon carbide switching devices, etc., or resonant switching technology, multi-level topology, etc. are mainly used to improve switching efficiency and reduce switching losses.

[0005] However, research has found that the current DC-DC non-isolated bidirectional converter always adopts a relatively single power supply method. For example, by converting the power stored in the lithium battery and providing it to the load, it not only has the problem of low flexibility, but also severely limits the application scenarios of the DC-DC non-isolated bidirectional converter. Summary of the invention

[0006] In order to overcome the technical problem that the related technology converts the electricity stored in the lithium battery and provides it to the load, which not only has low flexibility but also seriously limits the application scenarios of the DC-DC non-isolated bidirectional converter, the present disclosure provides a converter bidirectional control circuit and a driving method thereof, aiming to improve the flexibility of the DC-DC non-isolated bidirectional converter and enrich the application scenarios of the DC-DC non-isolated bidirectional converter.

[0007] According to a first aspect of an embodiment of the present disclosure, there is provided a bidirectional converter control circuit, comprising: a controller, a first drive circuit and a second drive circuit connected to the controller, a bidirectional conversion circuit connected to the first drive circuit and the second drive circuit respectively, and a solar energy conversion circuit connected to the bidirectional conversion circuit;

[0008] The bidirectional conversion circuit comprises a plurality of switch elements, an inductor element and an energy storage element, wherein the plurality of switch elements are evenly divided into two groups connected in series, and the connection points formed between the adjacent switch elements in series are connected to the connection points formed between the other group of adjacent switch elements in series through the inductor element to form an H bridge, and the energy storage element is respectively connected in parallel to the head and tail of the two groups of switch elements in series on the left and right sides of the H bridge;

[0009] The sampling voltage output terminal of the solar energy conversion circuit is connected to the sampling voltage input terminal of the controller, the current output terminal of the solar energy conversion circuit is connected to the current input terminal of the bidirectional conversion circuit, and the current output terminal of the bidirectional conversion circuit is configured to be connected to a load;

[0010] The controller is used to generate a first control signal for controlling the on / off of the switch element at the upper end of the H-bridge and a second control signal for controlling the on / off of the switch element at the lower end of the H-bridge according to the sampled voltage received by the sampled voltage input terminal, so as to adjust the output power of the solar energy conversion circuit;

[0011] The first driving circuit is used to convert the first control signal into a first driving signal, and output the first driving signal to the switch element at the upper end of the H bridge to control the on and off of the switch element at the upper end of the H bridge;

[0012] The second driving circuit is used to convert the second control signal into a second driving signal, and output the first driving signal to the switching element at the lower end of the H bridge to control the on and off of the switching element at the lower end of the H bridge;

[0013] The bidirectional conversion circuit is used to receive the first drive signal and the second drive signal, and execute the on-off of each of the switch elements, so as to store the voltage of the bidirectional conversion circuit provided by the solar energy conversion circuit into the inductive element and output it to the load.

[0014] In a possible implementation, the switch elements in the bidirectional conversion circuit are four MOS tubes, wherein the drain of the first MOS tube Q5 is configured to be connected to the current input end of the bidirectional conversion circuit and the current output end of the solar energy conversion circuit, the source of the first MOS tube Q5 is connected to the drain of the second MOS tube Q6 to form a left-side series structure of the H bridge, and the source of the second MOS tube Q6 is connected to the source of the fourth MOS tube Q8 and grounded after the connection;

[0015] The drain of the fourth MOS transistor Q8 is connected to the source of the third MOS transistor to form a right-side series structure of the H-bridge, and after the connection, it is connected to the connection point of the source of the first MOS transistor Q5 and the drain of the second MOS transistor Q6 through an inductor element to form a middle structure of the H-bridge;

[0016] The drain of the third MOS tube and the source of the fourth MOS tube Q8 are respectively constructed as the positive terminal and the negative terminal of the bidirectional conversion circuit;

[0017] The energy storage element is respectively connected in parallel between the drain of the first MOS tube Q5 and the source of the second MOS tube Q6, or connected in parallel between the drain of the third MOS tube Q7 and the source of the fourth MOS tube Q8;

[0018] The gate of the first MOS transistor Q5 and the gate of the third MOS transistor Q7 are respectively connected to the control signal output end of the first driving circuit, and the gate of the second MOS transistor Q6 and the gate of the fourth MOS transistor Q8 are respectively connected to the control signal output end of the second driving circuit.

[0019] In a possible implementation, the bidirectional conversion circuit is constructed as a forward BOOST circuit, the gate of the first MOS tube Q5 receives a high level and is turned on, the gate of the second MOS tube receives a low level and is turned off, the gate of the third MOS tube Q7 and the gate of the fourth MOS tube Q8 receive complementary PWM waves, and the DC voltage provided by the solar energy conversion circuit is boosted and output to the load;

[0020] The bidirectional conversion circuit is constructed as a forward BUCK circuit. The gate of the third MOS tube Q7 receives a high level and is turned on, the gate of the fourth MOS tube receives a low level and is turned off, the gate of the first MOS tube Q5 and the gate of the second MOS tube Q6 receive complementary PWM waves, and the DC voltage provided by the solar energy conversion circuit is reduced and output to the load.

[0021] In a possible implementation, the bidirectional conversion circuit is constructed as a reverse BOOST circuit, the gate of the third MOS tube Q7 receives a high level and is turned on, the gate of the fourth MOS tube receives a low level and is turned off, the gate of the first MOS tube Q5 and the gate of the second MOS tube Q6 receive complementary PWM waves, and the DC voltage provided by the positive terminal and the negative terminal of the bidirectional conversion circuit is boosted and output to the solar energy conversion circuit;

[0022] The bidirectional conversion circuit is constructed as a reverse BUCK circuit, the gate of the first MOS tube Q5 receives a high level to be turned on, the gate of the second MOS tube receives a low level to be turned off, the gate of the third MOS tube Q7 and the gate of the fourth MOS tube Q8 receive complementary PWM waves, and the DC voltage provided by the positive and negative terminals of the bidirectional conversion circuit is reduced and output to the solar energy conversion circuit.

[0023] In a possible implementation, the converter bidirectional control circuit further includes a current sampling circuit and a voltage sampling circuit;

[0024] The input end of the current sampling circuit is connected to the current output end of the solar energy conversion circuit, and the output end of the current sampling circuit is connected to the current input end of the bidirectional conversion circuit, or the input end of the current sampling circuit is connected to the positive terminal of the bidirectional conversion circuit, and the output end of the current sampling circuit is connected to the load;

[0025] The voltage sampling circuit is connected between the positive terminal and the negative terminal of the converter bidirectional control circuit.

[0026] In one possible implementation, the converter bidirectional control circuit also includes an auxiliary power supply circuit with different voltage levels, which converts the working power into voltages of different sizes and provides them to the controller, the first drive circuit and the second drive circuit as working power.

[0027] According to a second aspect of an embodiment of the present disclosure, a driving method of a bidirectional converter control circuit is provided, which is applied to the converter bidirectional control circuit described in any one of the first aspects, comprising:

[0028] Obtaining the output voltage output by the sampling voltage output terminal of the solar energy conversion circuit at any sampling time through the sampling voltage input terminal of the controller, and obtaining the output current output by the current output terminal of the solar energy conversion circuit at any sampling time;

[0029] When the bus voltage is less than a preset voltage threshold, determining the output power of the solar energy conversion circuit at any sampling time according to the output current and the output voltage corresponding to any sampling time;

[0030] Determine a constant current output conversion factor according to a preset control ratio, the output power corresponding to a current sampling moment, and the output power corresponding to a previous sampling moment before the current sampling moment;

[0031] Determine, according to the magnitude of the constant current output conversion factor, a magnitude relationship between the output current corresponding to a current sampling moment and the output current corresponding to a previous sampling moment of the current sampling moment;

[0032] According to the magnitude relationship, the constant current target value is adjusted at a preset ratio to adjust the actual output power of the solar energy conversion circuit, thereby achieving voltage-limited constant current output of electrical energy to the load.

[0033] In one possible implementation, the output voltage is determined by:

[0034] Determine the voltage error value between the actual sampling voltage and the preset reference sampling voltage at any sampling time;

[0035] Perform proportional-integral-differential calculations based on the sampling period, the voltage error value at the current sampling moment, the voltage error values ​​corresponding to the two sampling moments before the current sampling moment, the proportional coefficient, the integral time constant, and the differential time constant to determine the output voltage difference between the previous sampling moment and the current sampling moment;

[0036] The output voltage at the current sampling moment is determined according to the output voltage at the previous sampling moment and the output voltage difference.

[0037] In one possible implementation, the output voltage is determined by the following formula:

[0038]

[0039] u(n)=u(n-1)+Δu

[0040] Among them, △u is the difference between the output at the n-1th sampling time and the nth sampling time, k p is the proportionality coefficient, T i is the integration time constant, T d is the differential time constant, e(n) is the voltage error value corresponding to the nth sampling moment, e (n-1) is the voltage error value corresponding to the n-1th sampling moment, e (n-2) is the voltage error value corresponding to the n-2th sampling moment, u(n) is the output voltage corresponding to the n-1th sampling moment, u(n-1) is the output voltage corresponding to the n-1th sampling moment, and T is the sampling period.

[0041] The technical solution provided by the embodiments of the present disclosure may have the following beneficial effects:

[0042] By adopting the bidirectional conversion circuit of H-bridge structure and combining the precise control of the switch element by the controller, the output voltage and current of the solar energy conversion circuit can be effectively regulated. It not only improves the energy conversion efficiency, but also ensures the stability of the output voltage and current, and meets the energy requirements of different loads.

[0043] Furthermore, the controller generates and outputs a control signal in real time according to the sampled voltage of the solar energy conversion circuit, which is converted into a drive signal through the first drive circuit and the second drive circuit to control the on and off of the upper and lower switch elements of the H bridge. The intelligent control method enables the entire system to automatically adjust the output power according to the actual situation of the solar energy conversion circuit and the load demand, thereby maximizing the utilization of energy.

[0044] Furthermore, the energy storage element is connected in parallel at the beginning and end of the switch elements connected in series on the left and right sides of the H-bridge, which effectively smooths the voltage fluctuations and improves the stability and reliability of the system. At the same time, the introduction of the inductor element further enhances the filtering effect of the circuit and ensures the purity and stability of the output voltage. By adjusting the control strategy, compatibility and control of different energy conversion systems can be easily achieved. It has significant advantages in efficient energy conversion, intelligent control, system stability and reliability, flexibility and scalability, energy saving, emission reduction and environmental protection benefits. Thereby achieving the technical effect of improving the flexibility of the DC-DC non-isolated bidirectional converter and enriching the application scenarios of the DC-DC non-isolated bidirectional converter.

[0045] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0047] Figure 1 is a circuit diagram of a bidirectional converter control circuit according to an exemplary embodiment.

[0048] Figure 2 is a circuit diagram of a solar energy conversion circuit according to an exemplary embodiment.

[0049] Figure 3 is a circuit diagram of a first driving circuit according to an exemplary embodiment.

[0050] Figure 4 is a circuit diagram of a second driving circuit according to an exemplary embodiment.

[0051] Figure 5 is a circuit diagram of a bidirectional conversion circuit according to an exemplary embodiment.

[0052] Figure 6 is a circuit diagram of a converter bidirectional control circuit according to an exemplary embodiment.

[0053] Figure 7 is a circuit diagram of a current sampling circuit according to an exemplary embodiment.

[0054] Figure 8 is a circuit diagram of a voltage sampling circuit according to an exemplary embodiment.

[0055] Fig. 9 is a circuit diagram of an auxiliary power supply circuit according to an exemplary embodiment.

[0056] Fig.10 is a flow chart showing a driving method of a bidirectional converter control circuit according to an exemplary embodiment. DETAILED DESCRIPTION

[0057] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0058] Figure 1 is a circuit diagram of a bidirectional converter control circuit according to an exemplary embodiment. Figure 1 As shown, the bidirectional converter control circuit comprises:

[0059] A controller, a first drive circuit and a second drive circuit connected to the controller, a bidirectional conversion circuit connected to the first drive circuit and the second drive circuit respectively, and a solar energy conversion circuit connected to the bidirectional conversion circuit;

[0060] The controller can be a single-chip microcomputer. In the bidirectional converter control circuit, the solar energy conversion circuit is responsible for efficiently converting the captured solar energy into electrical energy for use by subsequent circuits. The solar energy conversion circuit not only requires high conversion efficiency, but also needs to ensure the stability and reliability of the output electrical energy. In order to achieve this goal, a close feedback mechanism is established between the solar energy conversion circuit and the controller.

[0061] Solar energy conversion circuits are usually based on the principle of photovoltaic effect, using photovoltaic panels to directly convert solar energy into electrical energy. Photovoltaic panels are composed of multiple photovoltaic cell units, which generate electromotive force under light conditions and output DC current. In order to match the needs of subsequent circuits, solar energy conversion circuits may also include functional modules such as voltage regulation, current limiting, and maximum power point tracking (MPPT). These modules work together to ensure that photovoltaic panels can output optimal electrical energy under different lighting and environmental conditions.

[0062] The bidirectional conversion circuit comprises a plurality of switch elements, an inductor element and an energy storage element, wherein the plurality of switch elements are evenly divided into two groups connected in series, and the connection points formed between the adjacent switch elements in series are connected to the connection points formed between the other group of adjacent switch elements in series through the inductor element to form an H bridge, and the energy storage element is respectively connected in parallel to the head and tail of the two groups of switch elements in series on the left and right sides of the H bridge;

[0063] Among them, the bidirectional conversion circuit adopts an H-bridge structure, which is composed of multiple switching elements (such as MOSFET or IGBT), inductance elements and energy storage elements (such as capacitors). The switching elements are evenly divided into two groups, each group is connected in series to form the upper and lower arms of the H-bridge. The inductance element is located in the center of the H-bridge, connecting the connection points of the upper and lower arms, playing the role of energy storage and filtering. The energy storage element is connected in parallel to the head and tail of the switch elements in series on the left and right sides of the H-bridge to smooth voltage fluctuations.

[0064] The sampling voltage output terminal of the solar energy conversion circuit is connected to the sampling voltage input terminal of the controller, the current output terminal of the solar energy conversion circuit is connected to the current input terminal of the bidirectional conversion circuit, and the current output terminal of the bidirectional conversion circuit is configured to be connected to a load;

[0065] Sampling voltage output and feedback mechanism: In the solar energy conversion circuit, the sampling voltage output terminal is responsible for real-time monitoring of the output voltage and passing it to the controller as a feedback signal. This step is crucial because it is directly related to whether the controller can accurately adjust the output power to meet the load demand.

[0066] The sampling voltage is usually obtained through a voltage divider circuit or a dedicated sampling circuit, which can accurately reduce the output voltage to an acceptable range for the controller. The sampling voltage output terminal is connected to the controller through an electrical connection (such as a wire or a trace on a printed circuit board) to ensure that the signal can be transmitted stably and accurately.

[0067] The controller receives the sampled voltage and adjusts the output power: The controller is the core component of the bidirectional converter control circuit. It is responsible for receiving the sampled voltage from the solar energy conversion circuit and generating corresponding control signals according to preset algorithms and strategies. These control signals are designed to adjust the on-off state of the switching elements in the bidirectional conversion circuit, thereby achieving precise control of the output power of the solar energy conversion circuit.

[0068] The controller may contain an analog-to-digital converter (ADC) to convert the received analog sampled voltage into a digital signal for subsequent digital processing. In the digital processing stage, the controller may use various control algorithms (such as PID control, fuzzy control, or neural network control) to calculate the required control signal. These algorithms are usually designed and optimized based on factors such as the system's dynamic model, load characteristics, and expected output power quality.

[0069] Finally, the controller outputs the calculated control signal to the drive circuit, which further converts it into a drive signal suitable for the operation of the switch element. These drive signals control the on and off states of the switch elements in the H-bridge bidirectional conversion circuit, thereby achieving precise regulation of the output power of the solar energy conversion circuit.

[0070] The interaction mechanism between the solar energy conversion circuit and the controller is the key to the bidirectional converter control circuit to achieve efficient and stable energy conversion. Through precise sampling voltage feedback and advanced control algorithms, the controller can adjust the output power in real time to ensure that the solar energy conversion circuit can output high-quality electrical energy under different conditions.

[0071] The controller is used to generate a first control signal for controlling the on / off of the switch element at the upper end of the H-bridge and a second control signal for controlling the on / off of the switch element at the lower end of the H-bridge according to the sampled voltage received by the sampled voltage input terminal, so as to adjust the output power of the solar energy conversion circuit;

[0072] Among them, see Figure 2 The solar energy conversion circuit shown is responsible for converting solar energy into electrical energy and feeding back real-time voltage information to the controller through the sampling voltage output terminal. The controller receives this sampling voltage as a basis for adjusting the output power.

[0073] The controller calculates the required output power through a built-in algorithm based on the received sampled voltage and generates a corresponding first control signal and a second control signal. The two control signals are used to control the on and off of the upper and lower switch elements of the H-bridge, respectively, so as to adjust the output power of the solar energy conversion circuit.

[0074] The first driving circuit is used to convert the first control signal into a first driving signal, and output the first driving signal to the switch element at the upper end of the H bridge to control the on and off of the switch element at the upper end of the H bridge;

[0075] The second driving circuit is used to convert the second control signal into a second driving signal, and output the first driving signal to the switching element at the lower end of the H bridge to control the on and off of the switching element at the lower end of the H bridge;

[0076] The first drive circuit and the second drive circuit receive the first control signal and the second control signal output by the controller respectively, and convert them into the first drive signal and the second drive signal suitable for the operation of the switch element. Then, the two drive signals are output to the switch elements at the upper and lower ends of the H bridge respectively to control their on and off states.

[0077] See also Figure 3 As shown, the first driving circuit is used as a High-Side Driver circuit, see Figure 4 As shown, the second driving circuit is used as a Low-Side Driver circuit, and the output end uses 1000μF, 470μF electrolytic capacitors and 10μF, 1μF, 100nF chip capacitors for filtering.

[0078] like Figure 3 As shown in the figure, the working principle of High-Side Driver is to provide high voltage through an external power supply or battery, and appropriately reduce and adjust it through the driving circuit to drive the high-side switching device. This design enables the high-side device to effectively control and regulate the current and power in the circuit.

[0079] For example, UCC21520DWR can be used as a driver chip to provide safe and reliable electrical isolation between input and output based on its isolation voltage of up to 5kV. The chip has fast switching and shutdown characteristics, which can achieve high-efficiency energy conversion and fast-response switching operations. It has high driving capability and is suitable for driving high-side switching devices (such as N-channel MOSFET). It can provide sufficient current and voltage to control the conduction and disconnection of high-side switching devices. The chip adopts a low-power design, which helps to reduce the energy consumption of the entire system. The UCC21520DWR chip integrates a variety of protection functions, including over-temperature protection, short-circuit protection, and over-current protection, to ensure the safety and reliability of the system. The chip is suitable for a wide operating temperature range and can operate under harsh environmental conditions. The chip has flexible pin configuration options, which is convenient for connection and integration with other circuits and devices.

[0080] The High-Side Driver circuit uses UCC21520DWR as the control chip, constructs a bootstrap circuit at its two output ends, and uses isolated power supply to make the MOSFET G pole voltage always higher than the S pole, providing a startup voltage between the gate and source for the two High-SideDriver MOSFETs of the main circuit.

[0081] See also Figure 4 As shown, the working principle of Low-Side Driver is to provide a power ground (ground potential) through an external power supply or battery, and appropriately adjust and amplify it through the driving circuit to drive the low-side switching device. This design enables the low-side device to effectively control and regulate the current and power in the circuit. The Low-Side Driver uses the IRS4427STRPBF chip as the driver chip of the Low-Side Drive circuit. The chip integrates two independent low-side drivers, each of which has very low output impedance and high driving capability, which makes it very suitable for applications that need to control two switching devices at the same time. In addition, the chip adopts a low-power design with low static current and low dynamic power consumption, which helps to reduce the energy consumption of the entire system. The IRS4427STRPBF also has fast switching and shutdown characteristics, which can achieve high-efficiency energy conversion and fast-response switching operations. It can provide sufficient current and voltage to control the conduction and disconnection of the low-side switching device. In the Low-Side Drive circuit, VGS is 10V, see Figure 4 As shown, the S pole is always grounded, so the G pole is always higher than the S pole. At this time, only a voltage greater than 10V needs to be directly provided to turn on the MOSFET.

[0082] Gate-source resistance: ① It can affect the switching speed of the MOSFET. A larger gate-source resistance will increase the time for charge injection and discharge, thereby delaying the switching process of the MOSFET, which may lead to a reduction in switching speed, especially in high-frequency applications. Therefore, a MOSFET with a low gate-source resistance is selected in this application to increase the switching speed. ② It determines the output impedance of the MOSFET, which represents the impedance of the output end of the MOSFET to the external circuit. A larger gate-source resistance will result in a higher output impedance, which reduces the MOSFET's ability to drive the external circuit; conversely, a smaller gate-source resistance will reduce the output impedance and improve the MOSFET's driving capability. A gate-source resistance of 10KΩ is used.

[0083] The bidirectional conversion circuit is used to receive the first drive signal and the second drive signal, and execute the on-off of each of the switch elements, so as to store the voltage of the bidirectional conversion circuit provided by the solar energy conversion circuit into the inductive element and output it to the load.

[0084] Among them, the bidirectional conversion circuit performs energy transmission: under the on-off control of the H-bridge switch element, the voltage provided by the solar energy conversion circuit is transmitted to the bidirectional conversion circuit. Through the energy storage and release of the inductor element and the rapid switching of the switch element, the bidirectional flow and efficient transmission of energy are realized. Finally, the regulated electric energy is output to the load end to meet the power demand of the load.

[0085] Among them, the bidirectional converter control circuit can be applied to a DC-DC bidirectional converter, which is a power converter that can realize bidirectional conversion of electric energy. It can convert the DC voltage of one power source into the DC voltage of another power source, while allowing current to flow in both directions. This bidirectional converter is often used in applications such as battery energy management systems, electric vehicle charging and discharging systems, and microgrids.

[0086] The first control signal and the second control signal can be generated based on pulse width modulation (PWM) technology, and the stability of the output voltage and current can be controlled by adjusting the on time and off time of the switch tube. The control strategy can be implemented based on fixed frequency PWM or variable frequency PWM.

[0087] Among them, input current control: In order to achieve bidirectional flow of electric energy, the DC-DC bidirectional converter needs to control the direction and magnitude of the input current. Usually, a current control loop is used to monitor the input current and control the direction and magnitude of the current by adjusting the working state of the switch tube.

[0088] Overcurrent protection: Bidirectional converters usually need to have overcurrent protection to prevent the current from exceeding the set safety range. Overcurrent protection can be achieved through current sensors and control loops. Once an overcurrent condition is detected, the system will take corresponding protection measures, such as reducing the switching frequency, reducing the output voltage, etc.

[0089] Feedback control: In order to maintain the stability of output voltage and current, bidirectional converters usually use a feedback control loop. This loop monitors the output voltage and current, compares the measurement results with the set value, and adjusts the working state of the switch tube to keep the output at the desired stable value.

[0090] The above technical solution uses a bidirectional conversion circuit with an H-bridge structure and combines the controller's precise control of the switch elements to achieve effective regulation of the output voltage and current of the solar energy conversion circuit. It not only improves the energy conversion efficiency, but also ensures the stability of the output voltage and current, meeting the energy requirements of different loads.

[0091] Furthermore, the controller generates and outputs a control signal in real time according to the sampled voltage of the solar energy conversion circuit, which is converted into a drive signal through the first drive circuit and the second drive circuit to control the on and off of the upper and lower switch elements of the H bridge. The intelligent control method enables the entire system to automatically adjust the output power according to the actual situation of the solar energy conversion circuit and the load demand, thereby maximizing the utilization of energy.

[0092] Furthermore, the energy storage element is connected in parallel at the beginning and end of the switch elements connected in series on the left and right sides of the H-bridge, which effectively smooths the voltage fluctuations and improves the stability and reliability of the system. At the same time, the introduction of the inductor element further enhances the filtering effect of the circuit and ensures the purity and stability of the output voltage. By adjusting the control strategy, compatibility and control of different energy conversion systems can be easily achieved. It has significant advantages in efficient energy conversion, intelligent control, system stability and reliability, flexibility and scalability, energy saving, emission reduction and environmental protection benefits. Thereby achieving the technical effect of improving the flexibility of the DC-DC non-isolated bidirectional converter and enriching the application scenarios of the DC-DC non-isolated bidirectional converter.

[0093] In one possible implementation, see Figure 5 and 6 As shown, the switch elements in the bidirectional conversion circuit are 4 MOS tubes, wherein the drain of the first MOS tube Q5 is constructed to be connected to the current input end of the bidirectional conversion circuit and the current output end of the solar energy conversion circuit, the source of the first MOS tube Q5 is connected to the drain of the second MOS tube Q6 to form the left series structure of the H bridge, and the source of the second MOS tube Q6 is connected to the source of the fourth MOS tube Q8 and grounded after the connection;

[0094] The drain of the fourth MOS transistor Q8 is connected to the source of the third MOS transistor to form a right-side series structure of the H-bridge, and after the connection, it is connected to the connection point of the source of the first MOS transistor Q5 and the drain of the second MOS transistor Q6 through an inductor element to form a middle structure of the H-bridge;

[0095] The drain of the third MOS tube and the source of the fourth MOS tube Q8 are respectively constructed as the positive terminal and the negative terminal of the bidirectional conversion circuit;

[0096] The energy storage element is respectively connected in parallel between the drain of the first MOS tube Q5 and the source of the second MOS tube Q6, or connected in parallel between the drain of the third MOS tube Q7 and the source of the fourth MOS tube Q8;

[0097] The gate of the first MOS transistor Q5 and the gate of the third MOS transistor Q7 are respectively connected to the control signal output end of the first driving circuit, and the gate of the second MOS transistor Q6 and the gate of the fourth MOS transistor Q8 are respectively connected to the control signal output end of the second driving circuit.

[0098] Among them, in the bidirectional converter control circuit, the bidirectional conversion circuit is the key component to achieve bidirectional energy flow and efficient conversion. Among them, the H-bridge structure composed of 4 MOS tubes (Q5, Q6, Q7, Q8) is the core to achieve this function. The following is a detailed explanation of the principle of the H-bridge structure:

[0099] The basic structure of the MOS tube H bridge: The first MOS tube Q5: Its drain is connected to the current input end of the bidirectional conversion circuit, and is also connected to the current output end of the solar energy conversion circuit, as the left upper arm of the H bridge. The second MOS tube Q6: Its drain is connected to the source of the first MOS tube Q5, forming the left half of the H bridge in series. Its source is grounded together with the source of the fourth MOS tube Q8, forming a common point between the left lower arm and the right side of the H bridge. The third MOS tube Q7: Its source is connected to the drain of the fourth MOS tube Q8, forming the right half of the H bridge in series. Its drain serves as the positive terminal of the bidirectional conversion circuit and outputs the regulated electric energy. The fourth MOS tube Q8: Its drain is connected to the source of the third MOS tube Q7, as the right lower arm of the H bridge. Its source is grounded together with the source of the second MOS tube Q6, and also serves as the negative terminal of the bidirectional conversion circuit.

[0100] The middle structure of the H-bridge: In the center of the H-bridge, the drain (i.e., the positive terminal) of the third MOS tube Q7 is connected to the connection between the source of the first MOS tube Q5 and the drain of the second MOS tube Q6 through an inductor. This inductor plays the role of energy storage and filtering, which can smooth voltage fluctuations and ensure the stability of the output voltage.

[0101] Parallel connection of energy storage elements: Energy storage elements (such as capacitors) are connected in parallel between the drain of the first MOS tube Q5 and the source of the second MOS tube Q6, and between the drain of the third MOS tube Q7 and the source of the fourth MOS tube Q8. These energy storage elements are used to provide necessary charges when the MOS tubes are switched to maintain stable operation of the circuit and reduce voltage fluctuations.

[0102] Drive circuit and control signal: The gates of the first MOS transistor Q5 and the third MOS transistor Q7 are respectively connected to the control signal output terminal of the first drive circuit to receive the first control signal from the controller. These signals control the conduction and cutoff of the MOS transistors, thereby adjusting the switch state of the upper arm of the H bridge.

[0103] The gates of the second MOS transistor Q6 and the fourth MOS transistor Q8 are respectively connected to the control signal output terminal of the second drive circuit to receive the second control signal from the controller. These signals also control the conduction and cutoff of the MOS transistors and adjust the switch state of the lower arm of the H bridge.

[0104] When the first MOS tube Q5 and the fourth MOS tube Q8 are turned on at the same time, the current flows from the solar energy conversion circuit through Q5 into the H bridge, passes through the inductor and flows out through Q8 to supply power to the load. At this time, the third MOS tube Q7 and the second MOS tube Q6 are in the cut-off state to prevent current backflow.

[0105] When the third MOS tube Q7 and the second MOS tube Q6 are turned on at the same time (in specific application scenarios, such as energy recovery or reverse power supply), the current can flow from the load end through Q7 into the H bridge, pass through the inductor element, and then flow out through Q6 to return to the power supply or energy storage device. At this time, Q5 and Q8 are in the off state.

[0106] That is to say, in the specific control process, if the MOS tube Q5 is turned on at a high level and the MOS tube Q6 is turned off at a low level, the MOS tube Q7 and the MOS tube Q8 complement the PWM wave to form a positive BOOST circuit;

[0107] If MOS tube Q7 is turned on at a high level and MOS tube Q8 is turned off at a low level, MOS tube Q5 and MOS tube Q6 complement PWM waves to form a forward BUCK circuit;

[0108] If MOS tube Q7 is turned on at a high level and MOS tube Q8 is turned off at a low level, then MOS tube Q5 and MOS tube Q6 complement PWM waves to form a reverse BOOST circuit;

[0109] If the MOS tube Q5 is turned on at a high level and the MOS tube Q6 is turned off at a low level, the MOS tube Q7 and the MOS tube Q8 complement each other in PWM wave to form a reverse BUCK circuit.

[0110] The above technical solution can achieve bidirectional flow and efficient conversion of energy in the H-bridge structure by precisely controlling the conduction and cutoff of the MOS tube and the synergistic effect of the inductor element and the energy storage element, meeting the needs of various application scenarios.

[0111] In a possible implementation, the bidirectional conversion circuit is constructed as a forward BOOST circuit, the gate of the first MOS tube Q5 receives a high level and is turned on, the gate of the second MOS tube receives a low level and is turned off, the gate of the third MOS tube Q7 and the gate of the fourth MOS tube Q8 receive complementary PWM waves, and the DC voltage provided by the solar energy conversion circuit is boosted and output to the load;

[0112] In the forward BOOST circuit mode, the goal is to boost the input DC voltage to a higher level. This is achieved by the following steps:

[0113] The first MOS transistor Q5 is turned on: when the gate of Q5 receives a high level signal, Q5 is turned on, allowing current to flow from the solar energy conversion circuit (i.e., the input source) through Q5 to the inductor L (usually connected in series with Q5). At this time, the second MOS transistor Q6 is turned off because its gate receives a low level, preventing current from passing.

[0114] Energy storage stage: During the conduction period of Q5, the input voltage charges the inductor L, and the capacitor C (located at the output end) provides a stable voltage to the load. In this process, the output voltage is slightly lower than or equal to the input voltage because the capacitor C is discharging to maintain the output voltage.

[0115] Complementary PWM control of the third and fourth MOS tubes Q7 and Q8: Subsequently, Q5 is turned off, and Q7 and Q8 perform switching operations according to the complementary PWM wave. If Q7 is turned on (high level), the energy in the inductor L is released to the output through Q7, and the capacitor C is charged to support the output voltage. Q8 is cut off (low level) during this period and does not participate in current conduction. When Q7 is cut off and Q8 is turned on, although the direct path is theoretically cut off, due to the freewheeling effect of the inductor L, the current will continue to flow to the output through the diode (usually the built-in body diode of Q8) or an additional freewheeling diode, maintaining the output voltage and allowing the capacitor C to be further charged. By adjusting the duty cycle of the PWM wave, the degree to which the output voltage is higher than the input voltage can be controlled.

[0116] The bidirectional conversion circuit is constructed as a forward BUCK circuit. The gate of the third MOS tube Q7 receives a high level and is turned on, the gate of the fourth MOS tube receives a low level and is turned off, the gate of the first MOS tube Q5 and the gate of the second MOS tube Q6 receive complementary PWM waves, and the DC voltage provided by the solar energy conversion circuit is reduced and output to the load.

[0117] In the forward buck circuit mode, the goal is to reduce the input DC voltage to a lower level. This is achieved by the following steps:

[0118] The third MOS transistor Q7 is turned on: when the gate of Q7 receives a high level signal, Q7 is turned on, allowing current to flow from the solar energy conversion circuit through the inductor L to the output end. At this time, the fourth MOS transistor Q8 is turned off because its gate receives a low level and does not participate in current conduction.

[0119] Energy storage and output stage: During the conduction period of Q7, the input voltage directly charges the inductor L and transfers energy to the output end, while the capacitor C is also charged to smooth the output voltage. Due to the energy storage effect of the inductor L, a relatively stable output voltage can be maintained even when Q7 is briefly turned off for PWM modulation.

[0120] Complementary PWM control of the first and second MOS tubes Q5 and Q6: In order to reduce the output voltage, Q5 and Q6 perform switching operations according to the complementary PWM wave. When Q5 is turned on (high level), it actually provides a freewheeling path for the inductor L at the moment when Q7 is turned off, helping to maintain current continuity and reduce voltage spikes. Q6 may be used as an auxiliary switch in some designs for more complex control strategies (such as synchronous rectification) to improve efficiency, but in the basic BUCK circuit, its key role may not be as significant as Q5. By adjusting the duty cycle of the PWM wave, the degree to which the output voltage is lower than the input voltage can be controlled.

[0121] In these two modes, the bidirectional conversion circuit achieves effective rise and fall of the DC voltage by precisely controlling the switching state of the MOS tube, thereby meeting the specific voltage requirements of different loads.

[0122] In a possible implementation, the bidirectional conversion circuit is constructed as a reverse BOOST circuit, the gate of the third MOS tube Q7 receives a high level and is turned on, the gate of the fourth MOS tube receives a low level and is turned off, the gate of the first MOS tube Q5 and the gate of the second MOS tube Q6 receive complementary PWM waves, and the DC voltage provided by the positive terminal and the negative terminal of the bidirectional conversion circuit is boosted and output to the solar energy conversion circuit;

[0123] Among them, the reverse BOOST circuit can increase the input DC voltage to a higher voltage level. When the gate of the third MOS tube Q7 receives a high-level signal, the third MOS tube Q7 is turned on to allow current to pass. At the same time, the gate of the fourth MOS tube Q8 receives a low-level signal, and the fourth MOS tube Q8 is turned off, blocking its corresponding current path. At this time, the gates of the first MOS tube Q5 and the second MOS tube Q6 receive complementary PWM (pulse width modulation) waveforms, which means that when the first MOS tube Q5 is turned on, the second MOS tube Q6 is turned off, and vice versa.

[0124] During the boost process, when the first MOS tube Q5 is turned on, the input power charges the inductor through the first MOS tube Q5, and the capacitor C (not explicitly mentioned in the figure or description, but usually present in such circuits) provides current to the load to maintain a stable output voltage. When Q5 is turned off and Q6 is turned on, since the current in the inductor cannot change suddenly, it will try to continue to flow through the path formed by Q6 and Q7. In this process, the magnetic field energy of the inductor is converted into electrical energy and superimposed on the input voltage, thereby achieving a voltage increase. This process is repeated with the periodic change of the PWM waveform, thereby generating a DC voltage higher than the input voltage at the output end.

[0125] The bidirectional conversion circuit is constructed as a reverse BUCK circuit, the gate of the first MOS tube Q5 receives a high level to be turned on, the gate of the second MOS tube receives a low level to be turned off, the gate of the third MOS tube Q7 and the gate of the fourth MOS tube Q8 receive complementary PWM waves, and the DC voltage provided by the positive and negative terminals of the bidirectional conversion circuit is reduced and output to the solar energy conversion circuit.

[0126] The reverse BUCK circuit is used to reduce the input DC voltage to a lower voltage level. When the gate of the first MOS tube Q5 receives a high-level signal, Q5 is turned on to allow current to flow. The gate of the second MOS tube Q6 receives a low-level signal and Q6 is turned off. At this time, the gates of the third MOS tube Q7 and the fourth MOS tube Q8 receive complementary PWM waveforms.

[0127] During the step-down process, while Q5 is on, the input power source directly supplies power to the load, while the inductor L stores energy. When Q5 is turned off and one of Q7 and Q8 (specifically Q7 or Q8 according to the PWM signal, but the description simplifies this process by pointing out that they receive complementary signals, meaning that one is on when the other is off) is turned on, the inductor releases its stored energy and continues to supply power to the load, but since the power source no longer directly supplies power at this time, but maintains the current through the energy released by the inductor, the output voltage is lower than the input voltage. This process is also repeated with the periodic changes of the PWM waveform, thereby generating a stable DC voltage at the output that is lower than the input voltage.

[0128] In summary, by precisely controlling the gate voltage of the MOS tube, the reverse BOOST circuit and the reverse BUCK circuit can respectively increase and decrease the voltage, provide the required DC voltage for the solar energy conversion circuit, and ensure the efficient operation of the entire system.

[0129] In a possible implementation, the converter bidirectional control circuit further includes a current sampling circuit and a voltage sampling circuit;

[0130] See also Figure 7 The current sampling circuit shown in the application adopts a high-side current sampling solution, and the high-side current sampling uses a chip with integrated current detection function. These chips usually use the Hall effect or the change of the resistance value to achieve current measurement, and convert the current into a digital signal through an internal voltage amplifier and an analog-to-digital converter. This solution has high accuracy and response speed. The current sampling circuit uses INA271AIDR as the control chip, and the electrical signal flowing through the 50 milliohm resistor is amplified by 20 times inside the chip, and then fed back to the microcontroller through the voltage follower controlled by LM358P.

[0131] Furthermore, considering that INA271AIDR has polarity, a G6S-2 relay is used, and the microcontroller sends high and low levels to control the attraction of the coil in the relay. The G6S-2 relay is disconnected when the level is high and is connected when the level is low. When the system is forward-conducting, the G6S-2 relay of the current sampling module at the forward input end is turned on, and the G6S-2 relay of the current sampling module at the forward output end is disconnected to prevent the INA271AIDR from burning out when subjected to reverse voltage; when the system is reverse-conducting, the G6S-2 relay of the current sampling module at the reverse input end is turned on, and the G6S-2 relay of the current sampling module at the reverse output end is disconnected to prevent the INA271AIDR from burning out when subjected to reverse voltage.

[0132] See also Figure 8 The voltage sampling circuit shown in the figure uses M358P as a dual operational amplifier chip, analog circuit amplification and signal processing, the input voltage is divided by a series resistor, and the divided voltage is fed back to the microcontroller after being controlled by the voltage follower of LM358P.

[0133] The input end of the current sampling circuit is connected to the current output end of the solar energy conversion circuit, and the output end of the current sampling circuit is connected to the current input end of the bidirectional conversion circuit, or the input end of the current sampling circuit is connected to the positive terminal of the bidirectional conversion circuit, and the output end of the current sampling circuit is connected to the load;

[0134] The voltage sampling circuit is connected between the positive terminal and the negative terminal of the converter bidirectional control circuit.

[0135] Among them, combined with the feedback signals of the current sampling circuit and the voltage sampling circuit, the controller can implement complex control algorithms, such as PID (proportional-integral-differential) control, to achieve precise voltage and current regulation. These algorithms dynamically adjust the switching state of the MOS tube according to the current and voltage deviations monitored in real time, thereby optimizing energy conversion efficiency, protecting the circuit from faults, and ensuring stable operation of the system under various load and input conditions.

[0136] In one possible implementation, see Fig. 9 As shown, the converter bidirectional control circuit also includes auxiliary power supply circuits with different voltage levels, and the auxiliary power supply circuit converts the working power into voltages of different sizes and provides them to the controller, the first drive circuit and the second drive circuit as working power.

[0137] Among them, in the High-Side Driver, it is in the high-side position, its source is connected to the load, and the drain is connected to the positive power supply. The requirement that the G pole voltage is greater than the S pole is to overcome the reverse bias of the PN junction between the internal channel and the drain of the MOSFET to ensure that the channel is fully open. If the MOSFET needs to be normally open, the D pole and S pole voltages are equal and greater than 12V, then the G pole voltage cannot be greater than the S pole; at this time, it is necessary to isolate the 12V and connect it to the S pole to make it always higher than the S pole; use a 12V lithium battery as the MOSFET turn-on voltage of the High-Side Driver. Figure 7 shown.

[0138] In Low-Side Drive, the S pole of MOSFET is directly grounded, so the G pole must be greater than the S pole, and 12V can directly power the G pole without isolation. In the auxiliary power circuit, U1 uses the XL1509 buck chip as the control chip of the auxiliary power circuit; XL1509 uses a fixed frequency PWM control mode and has a built-in power switch tube and switch current detection resistor, which can provide a stable output voltage.

[0139] Therefore, in the embodiment of the present disclosure, only the conversion chip in the auxiliary power supply circuit needs to be replaced to convert the power supply voltage into the operating voltage of the first drive circuit or the second drive circuit or the current sampling circuit or the voltage sampling circuit.

[0140] The above technical solution is a DC / DC non-isolated high-efficiency, high-power density bidirectional converter based on a non-reverse BUCK-BOOST circuit and PID algorithm. The controller controls the opening and closing of four MOS tubes, and the characteristics of the N-channel enhancement MOSFET itself to achieve bidirectional buck-boost of the circuit; the forward and reverse input voltage and current are sampled and fed back to the controller. After the PID algorithm is calculated, the microcontroller sends a complementary PWM wave, which then controls the entire system to achieve constant current and constant power input.

[0141] According to an embodiment of the present disclosure, there is also provided a driving method of a bidirectional converter control circuit, which is applied to the converter bidirectional control circuit described in any one of the above embodiments, see Fig.10 As shown, the method includes:

[0142] In step S11, the output voltage output by the sampling voltage output terminal of the solar energy conversion circuit at any sampling time is obtained through the sampling voltage input terminal of the controller, and the output current output by the current output terminal of the solar energy conversion circuit at any sampling time is obtained;

[0143] In the disclosed embodiment, the solar energy conversion circuit may include a voltage sensor or a voltage divider circuit for scaling down the actual output voltage into a range suitable for processing by the controller. The controller reads the scaled-down voltage value through its internal analog-to-digital converter (ADC), thereby indirectly knowing the actual output voltage.

[0144] Similarly, current sensors, such as Hall sensors or shunt resistors, are also included in solar energy conversion circuits to measure the output current. These sensors convert the current into a voltage signal, which is then fed into the controller's ADC for digitization.

[0145] In order to accurately reflect the working state of the circuit, the controller will sample the voltage and current at a fixed time interval (i.e., sampling period). These sampled values ​​are used for subsequent calculations and control decisions.

[0146] In step S12, when the bus voltage is less than a preset voltage threshold, the output power of the solar energy conversion circuit at any sampling time is determined according to the output current and the output voltage corresponding to any sampling time;

[0147] Among them, when the bus voltage is less than the preset voltage threshold, the output power of the solar energy conversion circuit at any sampling moment is determined according to the output current and output voltage corresponding to the sampling moment. For example, when the bus voltage is lower than 12.6V and the voltage of each cascade battery is normal, the boost constant current output is achieved through the constant current PID control algorithm.

[0148] The output power P is equal to the output voltage V multiplied by the output current I (P = V * I). When the bus voltage is lower than the preset threshold, it means that the system may be in the startup phase or the load is light. At this time, the current needs to be limited to protect the circuit or optimize energy utilization. For example, t n-1 At this moment, the solar output power P n-1 =Uin n-1 ×Iin n-1 , boost constant current output Iout n-1 .t n At this moment, the solar output power P n =Uin n ×Iin n .

[0149] The preset voltage threshold is set according to system design and safety requirements to determine whether it is necessary to enter the voltage-limited constant current mode. When the bus voltage is lower than this threshold, the controller will start to execute the voltage-limited constant current control strategy.

[0150] In step S13, a constant current output conversion factor is determined according to a preset control ratio, the output power corresponding to the current sampling moment, and the output power corresponding to the previous sampling moment of the current sampling moment;

[0151] Among them, the boost constant current output is transformed to meet the constant current output conversion factor α=β×(P n -P n-1 ), β is the preset control ratio, which is used to limit the regulation intensity of the constant current output conversion factor α.

[0152] In step S14, according to the size of the constant current output conversion factor, the magnitude relationship between the output current corresponding to the current sampling moment and the output current corresponding to the previous sampling moment of the current sampling moment is determined;

[0153] In step S15, according to the magnitude relationship, the constant current target value is adjusted at a preset ratio to adjust the actual output power of the solar energy conversion circuit to achieve voltage-limited constant current output of electrical energy to the load.

[0154] Among them, boost constant current output Iout n =Iout n-1 ×(1+β×(P n -P n-1 )), when P n >P n-1 When α>0, Iout n >Iout n-1 , the output power will increase proportionally. n <P n-1 When α<0, Iout n<Iout n-1 , the output power will decrease proportionally. By continuously increasing and decreasing Iout, according to the volt-ampere characteristics of the solar panel load, when Iout n ≠Iout n-1 , P n ≈P n-1 When , the power reaches its peak value, which is the maximum power point of solar energy.

[0155] When the light angle changes significantly or the output voltage of the solar panel drops sharply, it is necessary to find the maximum power point again to ensure the correct operation of the solar power supply.

[0156] In one possible implementation, the output voltage is determined by:

[0157] Determine the voltage error value between the actual sampling voltage and the preset reference sampling voltage at any sampling time;

[0158] Perform proportional-integral-differential calculations based on the sampling period, the voltage error value at the current sampling moment, the voltage error values ​​corresponding to the two sampling moments before the current sampling moment, the proportional coefficient, the integral time constant, and the differential time constant to determine the output voltage difference between the previous sampling moment and the current sampling moment;

[0159] The output voltage at the current sampling moment is determined according to the output voltage at the previous sampling moment and the output voltage difference.

[0160] Specifically, the constant pressure controller and the constant current controller are two independent PID controllers. When the constant pressure controller is used, the constant current controller is suspended. Conversely, when the constant pressure controller is used, the constant current controller is suspended.

[0161] In the continuous analog PID formula, e(t) is the error between the actual value and the reference value of the system at any time t, k p is the proportionality coefficient, T I is the integration time constant, T I The larger the value is, the slower the improvement of the static error of the system. D is the differential time constant, T D The larger it is, the more obvious the differential effect is, reflecting the speed of error change. Determine the following relationship:

[0162]

[0163] PID calculation is performed based on the difference between the actual value and the reference value at any time to obtain the proportional integral differential result;

[0164] After discrete sampling, as shown in the following formula, T is the sampling period, e(n) is the system output and reference error at the nth sampling time, e(n-1) is the system output and reference error at the n-1th sampling time, and e(i) is the historical value of the error at each sampling starting from 0, that is, the value of i is 0, 1, 2...n. Since the PID output may exceed the allowable value, the output needs to be limited, and when the output is limited, the integral accumulation part should also be limited at the same time to prevent the integral from continuing to accumulate when the output remains unchanged.

[0165]

[0166] To simplify the algorithm and omit the operations such as integral limiting, the output of u(n-1) at time n-1 is derived as follows:

[0167]

[0168] From the above formula, it can be deduced that:

[0169]

[0170] Δu is the difference between the output at the n-1th sampling and the nth sampling. Since u(n-1) is the PID output at the n-1th sampling when calculating the nth time, the nth output is:

[0171] u(n)=u(n-1)+Δu

[0172] In this way, the incremental PID algorithm can be selected to achieve constant pressure, constant current and constant speed functions.

[0173] In one possible implementation, the output voltage is determined by the following formula:

[0174]

[0175] u(n)=u(n-1)+Δu

[0176] Among them, △u is the difference between the output at the n-1th sampling time and the nth sampling time, k p is the proportionality coefficient, T i is the integration time constant, T d is the differential time constant, e (n) is the voltage error value corresponding to the nth sampling moment, e (n-1) is the voltage error value corresponding to the n-1th sampling moment, e (n-2) is the voltage error value corresponding to the n-2th sampling moment, u(n) is the output voltage corresponding to the n-1th sampling moment, u(n-1) is the output voltage corresponding to the n-1th sampling moment, and T is the sampling period.

[0177] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the present disclosure. This application is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary technical means in the art that are not disclosed in the present disclosure. The specification and examples are to be considered as exemplary only, and the true scope and spirit of the present disclosure are indicated by the following claims.

[0178] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A converter bidirectional control circuit, characterized in that: include: A controller, a first drive circuit and a second drive circuit connected to the controller, a bidirectional conversion circuit connected to the first drive circuit and the second drive circuit respectively, and a solar energy conversion circuit connected to the bidirectional conversion circuit; The bidirectional conversion circuit comprises a plurality of switch elements, an inductor element and an energy storage element, wherein the plurality of switch elements are evenly divided into two groups connected in series, and the connection points formed between the adjacent switch elements in series are connected to the connection points formed between the other group of adjacent switch elements in series through the inductor element to form an H bridge, and the energy storage element is respectively connected in parallel to the head and tail of the two groups of switch elements in series on the left and right sides of the H bridge; The sampling voltage output terminal of the solar energy conversion circuit is connected to the sampling voltage input terminal of the controller, the current output terminal of the solar energy conversion circuit is connected to the current input terminal of the bidirectional conversion circuit, and the current output terminal of the bidirectional conversion circuit is configured to be connected to a load; The controller is used to generate a first control signal for controlling the on / off of the switch element at the upper end of the H-bridge and a second control signal for controlling the on / off of the switch element at the lower end of the H-bridge according to the sampled voltage received by the sampled voltage input terminal, so as to adjust the output power of the solar energy conversion circuit; The first driving circuit is used to convert the first control signal into a first driving signal, and output the first driving signal to the switch element at the upper end of the H bridge to control the on and off of the switch element at the upper end of the H bridge; The second driving circuit is used to convert the second control signal into a second driving signal, and output the first driving signal to the switching element at the lower end of the H bridge to control the on and off of the switching element at the lower end of the H bridge; The bidirectional conversion circuit is used to receive the first drive signal and the second drive signal, and execute the on and off of each of the switch elements, so as to store the voltage of the bidirectional conversion circuit provided by the solar energy conversion circuit into the inductive element and output it to the load.

2. The converter bidirectional control circuit according to claim 1, characterized in that: The switch elements in the bidirectional conversion circuit are four MOS tubes, wherein the drain of the first MOS tube Q5 is configured to be connected to the current input end of the bidirectional conversion circuit and the current output end of the solar energy conversion circuit, the source of the first MOS tube Q5 is connected to the drain of the second MOS tube Q6 to form a left-side series structure of the H bridge, and the source of the second MOS tube Q6 is connected to the source of the fourth MOS tube Q8 and grounded after the connection; The drain of the fourth MOS transistor Q8 is connected to the source of the third MOS transistor to form a right-side series structure of the H-bridge, and after the connection, it is connected to the connection point of the source of the first MOS transistor Q5 and the drain of the second MOS transistor Q6 through an inductor element to form a middle structure of the H-bridge; The drain of the third MOS tube and the source of the fourth MOS tube Q8 are respectively constructed as the positive terminal and the negative terminal of the bidirectional conversion circuit; The energy storage element is respectively connected in parallel between the drain of the first MOS tube Q5 and the source of the second MOS tube Q6, or connected in parallel between the drain of the third MOS tube Q7 and the source of the fourth MOS tube Q8; The gate of the first MOS transistor Q5 and the gate of the third MOS transistor Q7 are respectively connected to the control signal output end of the first driving circuit, and the gate of the second MOS transistor Q6 and the gate of the fourth MOS transistor Q8 are respectively connected to the control signal output end of the second driving circuit.

3. The converter bidirectional control circuit according to claim 2, characterized in that: The bidirectional conversion circuit is constructed as a forward BOOST circuit, the gate of the first MOS tube Q5 receives a high level to be turned on, the gate of the second MOS tube receives a low level to be turned off, the gate of the third MOS tube Q7 and the gate of the fourth MOS tube Q8 receive complementary PWM waves, and the DC voltage provided by the solar energy conversion circuit is boosted and output to the load; The bidirectional conversion circuit is constructed as a forward BUCK circuit. The gate of the third MOS tube Q7 receives a high level and is turned on, the gate of the fourth MOS tube receives a low level and is turned off, the gate of the first MOS tube Q5 and the gate of the second MOS tube Q6 receive complementary PWM waves, and the DC voltage provided by the solar energy conversion circuit is reduced and output to the load.

4. The converter bidirectional control circuit according to claim 2, characterized in that: The bidirectional conversion circuit is constructed as a reverse BOOST circuit, the gate of the third MOS tube Q7 receives a high level to be turned on, the gate of the fourth MOS tube receives a low level to be turned off, the gate of the first MOS tube Q5 and the gate of the second MOS tube Q6 receive complementary PWM waves, and the DC voltage provided by the positive terminal and the negative terminal of the bidirectional conversion circuit is boosted and output to the solar energy conversion circuit; The bidirectional conversion circuit is constructed as a reverse BUCK circuit, the gate of the first MOS tube Q5 receives a high level to be turned on, the gate of the second MOS tube receives a low level to be turned off, the gate of the third MOS tube Q7 and the gate of the fourth MOS tube Q8 receive complementary PWM waves, and the DC voltage provided by the positive and negative terminals of the bidirectional conversion circuit is reduced and output to the solar energy conversion circuit.

5. The converter bidirectional control circuit according to any one of claims 1 to 4, characterized in that: The converter bidirectional control circuit also includes a current sampling circuit and a voltage sampling circuit; The input end of the current sampling circuit is connected to the current output end of the solar energy conversion circuit, and the output end of the current sampling circuit is connected to the current input end of the bidirectional conversion circuit, or the input end of the current sampling circuit is connected to the positive terminal of the bidirectional conversion circuit, and the output end of the current sampling circuit is connected to the load; The voltage sampling circuit is connected between the positive terminal and the negative terminal of the converter bidirectional control circuit.

6. The converter bidirectional control circuit according to any one of claims 1 to 4, characterized in that: The converter bidirectional control circuit also includes auxiliary power supply circuits of different voltage levels, which convert working power into voltages of different magnitudes and provide them to the controller, the first drive circuit and the second drive circuit as working power.

7. A driving method for a bidirectional converter control circuit, characterized in that: A converter bidirectional control circuit applied to any one of claims 1 to 6, comprising: Obtaining the output voltage output by the sampling voltage output terminal of the solar energy conversion circuit at any sampling time through the sampling voltage input terminal of the controller, and obtaining the output current output by the current output terminal of the solar energy conversion circuit at any sampling time; When the bus voltage is less than a preset voltage threshold, determining the output power of the solar energy conversion circuit at any sampling time according to the output current and the output voltage corresponding to any sampling time; Determine a constant current output conversion factor according to a preset control ratio, the output power corresponding to a current sampling moment, and the output power corresponding to a previous sampling moment before the current sampling moment; Determine, according to the magnitude of the constant current output conversion factor, a magnitude relationship between the output current corresponding to a current sampling moment and the output current corresponding to a previous sampling moment of the current sampling moment; According to the magnitude relationship, the constant current target value is adjusted at a preset ratio to adjust the actual output power of the solar energy conversion circuit, thereby achieving voltage-limited constant current output of electrical energy to the load.

8. The driving method of the bidirectional converter control circuit according to claim 7, characterized in that: The output voltage is determined as follows: Determine the voltage error value between the actual sampling voltage and the preset reference sampling voltage at any sampling time; Perform proportional-integral-differential calculations based on the sampling period, the voltage error value at the current sampling moment, the voltage error values ​​corresponding to the two sampling moments before the current sampling moment, the proportional coefficient, the integral time constant, and the differential time constant to determine the output voltage difference between the previous sampling moment and the current sampling moment; The output voltage at the current sampling moment is determined according to the output voltage at the previous sampling moment and the output voltage difference.

9. The driving method of the bidirectional converter control circuit according to claim 8, characterized in that: The output voltage is determined by the following formula: u(n)=u(n-1)+Δu Among them, △u is the difference between the output at the n-1th sampling time and the nth sampling time, k p is the proportionality coefficient, T i is the integration time constant, T d is the differential time constant, e (n) is the voltage error value corresponding to the nth sampling moment, e (n-1) is the voltage error value corresponding to the n-1th sampling moment, e (n-2) is the voltage error value corresponding to the n-2th sampling moment, u(n) is the output voltage corresponding to the n-1th sampling moment, u(n-1) is the output voltage corresponding to the n-1th sampling moment, and T is the sampling period.

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