Multi-port converter for optical storage system and power supply system
By designing a multi-port converter, employing a two-phase interleaved parallel boost circuit and a dual active bridge circuit, the problem of low integration in traditional modular DC-DC-AC power supply systems is solved. This achieves improved device reuse rate and reduced cost, adapts to the intermittency and randomness of photovoltaic power generation, and enhances system stability and efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-19
- Publication Date
- 2026-04-07
AI Technical Summary
Traditional modular DC-DC-AC power supply systems have low system integration, low component reuse rate, large size, and high cost, making it difficult to effectively address the intermittency and randomness of photovoltaic power generation.
A multi-port converter is adopted, including a two-phase interleaved parallel boost circuit and a dual active bridge circuit. By sharing six high-frequency switching transistors, energy transfer between the photovoltaic port and the battery port and between the battery port and the AC bus port are realized, thereby improving system integration and device reuse rate.
The system size was reduced, costs were lowered, and bidirectional power flow between photovoltaics, batteries, and AC buses was achieved through control strategies, adapting to energy management needs under different operating conditions and improving system stability and efficiency.
Smart Images
Figure CN121813873A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of new energy technology, and in particular to a multi-port converter and power supply system for photovoltaic energy storage systems. Background Technology
[0002] With the continued growth of global demand for clean energy, solar energy, as a key component of the renewable energy system, is gradually increasing its share in the energy structure. Photovoltaic power generation, with its abundant resources and clean, pollution-free operation, is highly favored. However, photovoltaic power generation also has some inherent limitations, which pose challenges to the stable operation of the power system and the efficient use of energy. Photovoltaic power generation is significantly intermittent and random; its output depends on the intensity and duration of sunlight and is significantly affected by day-night cycles and weather changes (such as cloudy days, rainy days, and cloud cover). This intermittency and randomness make it difficult for wind and solar power to provide a stable and reliable power supply like traditional energy sources. When photovoltaic power is connected to the grid, it causes fluctuations in grid frequency and voltage, increasing the complexity of grid dispatching and control, and may even jeopardize the safe and stable operation of the grid. To address the intermittency and randomness of photovoltaic power, a photovoltaic-storage system is constructed by introducing battery energy storage technology to effectively smooth the output power of photovoltaic power and achieve the function of "peak shaving and valley filling."
[0003] Modular DC-DC-AC power supply systems are the core component of photovoltaic-storage systems, enabling energy conversion, control, and distribution. By modularly integrating DC-DC conversion (DC-DC) and DC-AC inversion (DC-AC) functions, they can address issues related to photovoltaic power output fluctuations, energy storage charging and discharging management, and AC load / grid connection requirements. Traditional modular DC-DC-AC power supply systems typically employ a cascaded architecture of multiple two-port DC-DC converters and subsequent DC-AC inverters, achieving energy transfer between photovoltaics, batteries, and the AC bus through multi-stage power conversion. While this approach achieves power decoupling between the front and rear stages, traditional two-port DC-DC converters operate independently, resulting in low system integration, low component reuse, large size, and high cost. Summary of the Invention
[0004] This application provides a multi-port converter and power supply system for photovoltaic energy storage systems, which can improve system integration and device reuse rate, thereby reducing system size and cost.
[0005] A first aspect of this application provides a multi-port converter for a photovoltaic-storage system. The multi-port converter includes a first high-frequency switch, a second high-frequency switch, a third high-frequency switch, a fourth high-frequency switch, a fifth high-frequency switch, a sixth high-frequency switch, a seventh high-frequency switch, an eighth high-frequency switch, a ninth high-frequency switch, a tenth high-frequency switch, a first inductor, a second inductor, and a high-frequency transformer; wherein: Energy is transmitted between the photovoltaic port and the battery port through a two-phase interleaved parallel boost circuit. The two-phase interleaved parallel boost circuit includes a first high-frequency switch, a second high-frequency switch, a third high-frequency switch, a fourth high-frequency switch, a fifth high-frequency switch, a sixth high-frequency switch, a first inductor, and a second inductor. The battery port transmits energy to the AC bus port through a dual active bridge circuit. The dual active bridge circuit includes two full-bridge circuits and the high-frequency transformer. One of the full-bridge circuits includes a first high-frequency switch, a second high-frequency switch, a third high-frequency switch, a fourth high-frequency switch, a fifth high-frequency switch, and a sixth high-frequency switch. The other full-bridge circuit includes a seventh high-frequency switch, an eighth high-frequency switch, a ninth high-frequency switch, and a tenth high-frequency switch. One of the full-bridge circuits is connected to the primary winding of the high-frequency transformer, and the other full-bridge circuit is connected to the secondary winding of the high-frequency transformer.
[0006] Optionally, the positive terminal of the battery port is connected to the drain of the first high-frequency switching transistor and the fourth high-frequency switching transistor; the source of the first high-frequency switching transistor is connected to the drain of the second high-frequency switching transistor and one end of the first inductor; the source of the fourth high-frequency switching transistor is connected to the drain of the fifth high-frequency switching transistor and one end of the second inductor; the source of the second high-frequency switching transistor and the drain of the third high-frequency switching transistor are connected to one end of the primary winding of the high-frequency transformer; the source of the fifth high-frequency switching transistor and the drain of the sixth high-frequency switching transistor are connected to the other end of the primary winding of the high-frequency transformer; the positive terminal of the photovoltaic port is connected to the other end of the first inductor and the second inductor; and the negative terminals of the battery port and the photovoltaic port are connected to the source of the third high-frequency switching transistor and the source of the sixth high-frequency switching transistor.
[0007] Optionally, one of the full-bridge circuits further includes a leakage inductance and a capacitor, wherein the source of the second high-frequency switch and the drain of the third high-frequency switch are connected to one end of the primary winding of the high-frequency transformer through the leakage inductance, and the source of the fifth high-frequency switch and the drain of the sixth high-frequency switch are connected to the other end of the primary winding of the high-frequency transformer through the capacitor.
[0008] Optionally, in the two-phase interleaved parallel boost circuit, the first high-frequency switch and the high-frequency switch consisting of the second and third high-frequency switches are complementary in conduction, and the fourth high-frequency switch and the high-frequency switch consisting of the fifth and sixth high-frequency switches are complementary in conduction. In the dual active bridge circuit, the high-frequency switch consisting of the first high-frequency switch and the second high-frequency switch is complementary to the third high-frequency switch, and the high-frequency switch consisting of the fourth high-frequency switch and the fifth high-frequency switch is complementary to the sixth high-frequency switch.
[0009] Optionally, the positive terminal of the AC bus port is connected to the drain of the seventh and ninth high-frequency switching transistors, the source of the seventh and eighth high-frequency switching transistors is connected to one end of the secondary winding of the high-frequency transformer, the source of the ninth and tenth high-frequency switching transistors is connected to the other end of the secondary winding of the high-frequency transformer, and the negative terminal of the AC bus port is connected to the source of the eighth and tenth high-frequency switching transistors.
[0010] Optionally, the multi-port converter further includes a third inductor, a fourth inductor, a first power frequency switch, and a second power frequency switch. The positive terminal of the AC bus port is connected to the drain of the seventh high-frequency switch, the ninth high-frequency switch, and the first power frequency switch. The source of the first power frequency switch and the drain of the second power frequency switch are connected to the other ends of the third inductor and the fourth inductor. The negative terminal of the AC bus port is connected to the source of the eighth high-frequency switch, the tenth high-frequency switch, and the second power frequency switch. The source of the seventh high-frequency switch and the drain of the eighth high-frequency switch are connected to the secondary winding of the high-frequency transformer and one end of the third inductor. The source of the ninth high-frequency switch and the drain of the tenth high-frequency switch are connected to the other end of the secondary winding of the high-frequency transformer and one end of the fourth inductor.
[0011] Optionally, the seventh and eighth high-frequency switching transistors are complementary in conduction, and the ninth and tenth high-frequency switching transistors are complementary in conduction.
[0012] Optionally, the first power frequency switch and the second power frequency switch are complementary in conduction and alternately conduction within the power frequency cycle, so that the polarity of the output voltage alternately reverses, thereby forming a sinusoidal AC voltage.
[0013] Optionally, the inward shift of the third high-frequency switch and the sixth high-frequency switch satisfies the following relationship: , in, Compared to the inward shift of the third high-frequency switch and the sixth high-frequency switch, Compared to the outward movement of the primary and secondary windings of the high-frequency transformer, The ratio of the number of turns in the secondary winding to the number of turns in the primary winding of the high-frequency transformer. This refers to the input voltage at the battery port. Let be the amplitude of the sinusoidal alternating voltage. Let be the angular frequency of the sinusoidal AC voltage.
[0014] A second aspect of this application provides a power supply system, which includes a multi-port converter as described in the first aspect of this application.
[0015] This application provides a multi-port converter and power supply system for photovoltaic-storage systems. The system comprises a two-phase interleaved parallel boost circuit for transmitting energy between the photovoltaic port and the battery port, and one full-bridge circuit of a dual active bridge circuit for transmitting energy between the battery port and the AC bus port, both sharing six high-frequency switching transistors. This application achieves port decoupling in its circuit structure while improving device reuse rate and reducing circuit cost. Compared to traditional modular DC-DC-AC power supply systems, it has higher integration and a smaller system size. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This application shows a schematic diagram of the structure of a conventional modular DC-DC-AC power supply system according to an embodiment of the present application; Figure 2 This paper shows a schematic diagram of the structure of a multi-port converter for an optical storage system according to an embodiment of this application; Figure 3 A schematic diagram of the modulation waveform and the voltage waveform at key terminals of a high-frequency switching transistor provided in one embodiment of this application is shown. Figure 4 A schematic diagram of the modulation waveform and the voltage and current waveforms at key terminals of a power frequency switching transistor provided in one embodiment of this application is shown. Figure 5 This invention provides a schematic diagram illustrating the operation of three operating modes of a multi-port converter for an optical storage system according to an embodiment of this application. Figure 6 This application shows a block diagram of a control strategy for a multi-port converter for an optical-storage system according to an embodiment of the present application. Figure 7A schematic diagram of a power supply system provided in one embodiment of this application is shown. Detailed Implementation
[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0019] Please refer to Figure 1 This figure illustrates a schematic diagram of a conventional modular DC-DC-AC power supply system according to an embodiment of this application. As shown, the output voltage and current of each photovoltaic array must pass through a two-port DC-DC converter and a two-port DC-AC inverter to enter the AC voltage bus, and then through a two-port DC-AC inverter and a two-port DC-DC converter to enter the battery voltage bus. , These represent the output voltage and output current of the photovoltaic port, respectively. , These represent the input voltage and input current at the AC bus port, respectively. , These represent the input voltage and input current at the battery port, respectively. It can be seen that in a traditional modular DC-DC-AC power supply system, at least two two-port DC-DC converters and two two-port DC-AC inverters are required for each photovoltaic array. Although this scheme can achieve power decoupling between the front and rear stages, the two-port DC-DC converters are independent of each other, resulting in low system integration, low device reuse rate, large size, and high cost.
[0020] To address the above technical issues, this application provides a multi-port converter and power supply system for photovoltaic energy storage systems, which can improve system integration and device reuse rate, thereby reducing system size and cost.
[0021] Please refer to Figure 2 This illustration shows a schematic diagram of a multiport converter for a photovoltaic energy storage system according to an embodiment of this application. The multiport converter includes a first high-frequency switching transistor. Second high-frequency switching transistor Third high-frequency switching transistor Fourth high-frequency switching transistor Fifth high-frequency switching transistor The sixth high-frequency switching transistor 7th high-frequency switching transistor Eighth high-frequency switching transistor Ninth high-frequency switching transistor 10th High-Frequency Switching Transistor First Inductor Second inductor and high-frequency transformers; among which: Energy is transferred between the photovoltaic port and the battery port via a two-phase interleaved parallel boost circuit, which includes the first high-frequency switching transistor. The second high-frequency switching transistor The third high-frequency switching transistor The fourth high-frequency switching transistor The fifth high-frequency switching transistor The sixth high-frequency switching transistor The first inductor and the second inductor ; The battery port transmits energy to the AC bus port through a dual active bridge circuit. The dual active bridge circuit includes two full-bridge circuits and the high-frequency transformer, one of which includes the first high-frequency switching transistor. The second high-frequency switching transistor The third high-frequency switching transistor The fourth high-frequency switching transistor The fifth high-frequency switching transistor and the sixth high-frequency switching transistor Another of the aforementioned full-bridge circuits includes the seventh high-frequency switching transistor. The eighth high-frequency switching transistor The ninth high-frequency switching transistor and the tenth high-frequency switching transistor One of the full-bridge circuits is connected to the primary winding of the high-frequency transformer, and the other full-bridge circuit is connected to the secondary winding of the high-frequency transformer.
[0022] Wherein, the positive terminal of the battery port is connected to the first high-frequency switching transistor. and the fourth high-frequency switching transistor The drain connection of the first high-frequency switching transistor The source of the second high-frequency switch The drain and the first inductor One end is connected to the fourth high-frequency switching transistor. The source of the fifth high-frequency switch transistor The drain and the second inductor One end is connected to the second high-frequency switching transistor. The source and the third high-frequency switch The drain of the fifth high-frequency switch is connected to one end of the primary winding of the high-frequency transformer. The source and the sixth high-frequency switch The drain of the photovoltaic port is connected to the other end of the primary winding of the high-frequency transformer, and the positive terminal of the photovoltaic port is connected to the first inductor. and the second inductor The other end is connected, and the negative terminal of the battery port and the photovoltaic port is connected to the third high-frequency switching transistor. The source and the sixth high-frequency switch The source connection.
[0023] Or as Figure 2 As shown, the battery is represented by an equivalent current source and a capacitor connected in parallel. The equivalent current source and capacitor of the battery are used to represent its input current. and input voltage That is, input current from and The drain flows in. Photovoltaics are also represented by a parallel equivalent current source and capacitor, which are used to represent the input current. and input voltage That is, input current from and It flows in from the other end.
[0024] Furthermore, one of the full-bridge circuits also includes a leakage inductance. and capacitor The second high-frequency switching transistor The source and the third high-frequency switch The drain electrode is through the leakage inductance The fifth high-frequency switching transistor is connected to one end of the primary winding of the high-frequency transformer. The source and the sixth high-frequency switch The drain of the capacitor is connected to the capacitor. It is connected to the other end of the primary winding of the high-frequency transformer.
[0025] In the two-phase interleaved parallel boost circuit, the first high-frequency switching transistor With the second high-frequency switching transistor and the third high-frequency switching transistor High-frequency switching transistors that are jointly conducting Complementary conduction, the fourth high-frequency switch With the fifth high-frequency switching transistor and the sixth high-frequency switching transistor High-frequency switching transistors that are jointly conducting Complementary conduction; In the dual active bridge circuit, the first high-frequency switching transistor and the second high-frequency switching transistor High-frequency switching transistors that are jointly conducting With the third high-frequency switching transistor Complementary conduction, the fourth high-frequency switch and the fifth high-frequency switching transistor High-frequency switching transistors that are jointly conducting With the sixth high-frequency switching transistor Complementary conduction.
[0026] The positive terminal of the AC bus port is connected to the seventh high-frequency switch. and the ninth high-frequency switching transistor The drain connection of the seventh high-frequency switch transistor The source and the eighth high-frequency switch The drain of the transistor is connected to one end of the secondary winding of the high-frequency transformer, and the ninth high-frequency switching transistor... The source and the tenth high-frequency switch The drain of the transistor is connected to the other end of the secondary winding of the high-frequency transformer, and the negative terminal of the AC bus port is connected to the eighth high-frequency switching transistor. and the tenth high-frequency switching transistor The source connection.
[0027] The multi-port converter also includes a third inductor. Fourth Inductor First power frequency switching transistor Second power frequency switching transistor The positive terminal of the AC bus port is connected to the seventh high-frequency switch. The ninth high-frequency switching transistor and the first power frequency switching transistor The drain connection of the first power frequency switching transistor The source and the second power frequency switch transistor The drain of the third inductor and the fourth inductor The other end is connected, and the negative terminal of the AC bus port is connected to the eighth high-frequency switch. The tenth high-frequency switching transistor and the second power frequency switching transistor The source connection; The seventh high-frequency switching transistor The source and the eighth high-frequency switch The drain of the high-frequency transformer and the secondary winding of the high-frequency transformer and the third inductor One end is connected to the ninth high-frequency switching transistor. The source and the tenth high-frequency switch The drain of the high-frequency transformer and the other end of the secondary winding of the high-frequency transformer and the fourth inductor One end is connected.
[0028] Among them, the seventh high-frequency switching transistor and the eighth high-frequency switching transistor Complementary conduction, the ninth high-frequency switch and the tenth high-frequency switching transistor Complementary conduction.
[0029] Among them, the first power frequency switching transistor and the second power frequency switching transistor The complementary conduction, and the alternating conduction within the power frequency cycle, cause the polarity of the output voltage to alternately reverse, thereby forming a sinusoidal AC voltage.
[0030] Or as Figure 2 As shown, the equivalent capacitance of the AC bus is... This indicates that the equivalent capacitance is... The positive electrode of the seventh high-frequency switch is connected to the positive electrode of the seventh high-frequency switch. The ninth high-frequency switching transistor and the first power frequency switching transistor Drain connection, equivalent capacitance The negative terminal of the eighth high-frequency switch is connected to the eighth high-frequency switch. The tenth high-frequency switching transistor and the second power frequency switching transistor The source connection.
[0031] Wherein, if the turns ratio of the primary winding to the secondary winding of the high-frequency transformer is 1:n, then the primary-bridge voltage of the high-frequency transformer is... The secondary inter-bridge voltage obtained after conversion Point A is the second high-frequency switching transistor. The source and the third high-frequency switch The midpoint, point B is the second high-frequency switching transistor. The source and the third high-frequency switch The midpoint, point C, is the seventh high-frequency switch. The source and the eighth high-frequency switch The midpoint, point D, is the ninth high-frequency switch. The source and the tenth high-frequency switch The midpoint. Secondary bridge voltage. After another full-bridge circuit to the equivalent capacitance Energy is transmitted, and the transmitted energy is represented by voltage. Equivalent representation. Voltage After the first power frequency switching transistor Second power frequency switching transistor First power frequency switching transistor Second power frequency switching transistor The alternating conduction during the power frequency cycle causes the polarity of the output voltage to reverse alternately, thus forming a sinusoidal alternating voltage. , , Let be the amplitude of the sinusoidal alternating voltage. The angular frequency of the sinusoidal alternating voltage is... The first power frequency switching transistor Second power frequency switching transistor The switching frequency.
[0032] Please refer to Figure 3 This diagram illustrates the modulation waveform and voltage waveform at key terminals of a high-frequency switching transistor according to an embodiment of this application. The high-frequency switching period of the high-frequency switching transistor is... each It includes 8 time periods. For example... Figure 3 As shown: hour, Conductive, Turn off, , , ; hour, Conductive, Turn off, , , ; hour, Conductive, Turn off, , , ; hour, Conductive, Turn off, , , ; hour, Conductive, Turn off, , , ; hour, Conductive, Turn off, , , ; hour, Conductive, Turn off, , , ; hour, Conductive, Turn off, , , .
[0033] Point E is the first high-frequency switching transistor. The source and the second high-frequency switch The midpoint, point F is the fourth high-frequency switch transistor. The source and the fifth high-frequency switch The midpoint, , , for , for , for D is the second high-frequency switching transistor. The third high-frequency switching transistor and the fifth high-frequency switching transistor The sixth high-frequency switching transistor The duty cycle for common conduction. The third high-frequency switch. and the sixth high-frequency switching transistor The duty cycle is 0.5. The third high-frequency switching transistor and the sixth high-frequency switching transistor The shift ratio is the ratio of the phase shift angle to 180°. It is easy to obtain that the first high-frequency switching transistor... and the fourth high-frequency switching transistor The duty cycle is (1-D), and the second high-frequency switch is... and the fifth high-frequency switching transistor The duty cycle is (0.5+D).
[0034] When energy is transferred between the photovoltaic port and the battery port through a two-phase interleaved parallel boost circuit, the duty cycle of one phase of the interleaved parallel boost circuit is the second high-frequency switch. and the third high-frequency switching transistor High-frequency switching transistors that are both conducting The duty cycle D. Similarly, the duty cycle of the other phase interleaved parallel boost circuit is the duty cycle of the fifth high-frequency switch. and the sixth high-frequency switching transistor High-frequency switching transistors that are both conducting The duty cycle D. Therefore, adjusting D can regulate the energy transferred from the photovoltaic port to the battery port.
[0035] When the battery port transfers energy to the AC bus port through the dual active bridge circuit, the third high-frequency switching transistor... and the sixth high-frequency switching transistor The duty cycle of each is 0.5, and the first high-frequency switching transistor... and the second high-frequency switching transistor High-frequency switching transistors that are both conducting Duty cycle, the fourth high-frequency switch and the fifth high-frequency switching transistor High-frequency switching transistors that are both conducting The duty cycle of all of them is 0.5, and is consistent with that of the third high-frequency switching transistor. and the sixth high-frequency switching transistor Complementary conduction. Therefore, the voltage at the midpoint of the primary side of the dual active bridge circuit is... The waveform is unaffected by D, and the power decoupling of the two-phase interleaved parallel boost circuit and the dual active bridge is achieved from the circuit structure perspective.
[0036] Due to the third high-frequency switching transistor and the sixth high-frequency switching transistor There is an inward shift compared to Therefore, the voltage at the midpoint of the primary side of the dual active bridge circuit is... The waveform is a three-level voltage square wave, i.e., the first high-frequency switching transistor. The second high-frequency switching transistor and the sixth high-frequency switching transistor When conducting, The third high-frequency switching transistor and the sixth high-frequency switching transistor When conducting, The third high-frequency switching transistor The fourth high-frequency switching transistor and the fifth high-frequency switching transistor When conducting, .
[0037] By adjusting the midpoint voltage of the primary and secondary sides and Compared to the outward movement This allows adjustment of the magnitude and direction of power transmission from the primary to the secondary side. When Power is transferred from the primary side to the secondary side; when The secondary side transfers power to the primary side. The seventh high-frequency switching transistor... Eighth high-frequency switching transistor Ninth high-frequency switching transistor 10th High-Frequency Switching Transistor The duty cycle of all of them is 0.5, and the seventh high-frequency switching transistor With the eighth high-frequency switching transistor Alternating conduction, ninth high-frequency switching transistor With the tenth high-frequency switching transistor Alternating conduction, secondary side midpoint voltage It is a two-level voltage square wave, namely the seventh high-frequency switching transistor. and the tenth high-frequency switching transistor When conducting, The eighth high-frequency switching transistor and the ninth high-frequency switching transistor When conducting, .
[0038] Please refer to Figure 4 This diagram illustrates the modulation waveform and voltage and current waveforms at key terminals of a power frequency switching transistor according to an embodiment of this application. By adjusting the inward shift... It can realize power factor correction and power flow control on the secondary side of high-frequency transformers, and improve the voltage at the midpoint of the primary side of the dual active bridge circuit. The durations of the high and low levels in the presented three-level waveform vary according to a sinusoidal law, and its overall envelope is approximately constant DC. After coupling via a high-frequency transformer, the secondary-side bridge voltage... It exhibits a square wave with alternating positive and negative values, and its amplitude envelope varies with twice the sine wave. At this time, the secondary output voltage... It exhibits a steamed bun wave shape, and after passing through a two-phase parallel interleaved step-down circuit, it reaches the first power frequency switching transistor. Second power frequency switching transistor A sinusoidal AC voltage is formed under the commutation action. The corresponding current The synchronous change is sinusoidal. The two tubes alternately conduct within the power frequency cycle, when... Conductive, When cut off, the output voltage is the positive half-cycle voltage. Conductive, At cutoff, the output voltage is the negative half-cycle, thus generating a sinusoidal AC voltage at the AC port. Under this control strategy, due to the AC bus voltage... The voltage exhibits a wave-like pattern rather than a constant DC voltage, resulting in pulsating power transmission. Therefore, the bus capacitor only needs to complete the charging and discharging of energy during the power pulsation period to maintain balance, eliminating the need for large-capacity capacitors and achieving stable power output, thus significantly reducing the size and cost of the bus capacitor.
[0039] Please refer to Figure 5 This document illustrates the operation of a multi-port converter (TPC) for a photovoltaic (PV) and energy storage (ESS) system according to an embodiment of this application. The TPC enables bidirectional power flow between the photovoltaic (PV), battery, and AC bus ports, adapting to energy management needs under different operating conditions. In the PV-to-battery-AC bus power supply mode, strong sunlight ensures sufficient PV energy. The PV system supplies power to both the AC bus and the battery via the TPC, storing excess PV energy in the battery. In the PV-battery-to-AC bus power supply mode, weaker sunlight reduces PV energy, making it insufficient to support AC bus power supply alone. The PV system and the discharging battery jointly supply power to the AC bus via the TPC, ensuring power supply to the load. In the PV-AC bus-to-battery power supply mode, the PV system and the AC bus jointly charge the battery via the TPC.
[0040] Please refer to Figure 6 This document illustrates a block diagram of a control strategy for a multiport converter for a photovoltaic-energy storage system according to an embodiment of this application. The multiport converter is controlled by three controllers: an input voltage regulator (IVR), a battery current / voltage regulator (BCR / BVR), and an output voltage regulator (OVR).
[0041] In this system, the IVR works in conjunction with the Maximum Power Point Tracking (MPPT) control at the photovoltaic input. The given voltage of the IVR is the voltage VMPPT output by the MPPT control, so that the photovoltaic input operates at the maximum power point and provides as much power as possible to the AC bus and the battery.
[0042] Among them, BCR / BVR controls the constant current or constant voltage charging of the battery port, and OVR controls the stability of the output capacitor voltage. Figure 3 and Figure 4 The modulation waveform diagram shows that there are three degrees of freedom (duty cycle D of the primary side two-phase interleaved parallel buck circuit, primary side high-frequency switching transistor). and Compared to the inward shift Compared to the outward shift of the original secondary side ), where D is obtained by minimum competition (min) between IVR and BVR / BCR. Always controlled by OVR.
[0043] The specific competition logic is as follows: When the photovoltaic input power is sufficient and the IVR is saturated, the BCR wins the competition first, charging the battery with a reasonable constant current. During this time, the battery voltage continuously increases. When the battery voltage reaches a certain value, to prevent overvoltage, the BVR wins the competition, causing the charging current to gradually decrease. When the photovoltaic input power is insufficient and both the BCR and BVR are saturated, the IVR wins the competition. At this time, the photovoltaic port always operates in MPPT state, supplying energy at maximum power. The phase-locked loop (PLL) tracks the AC voltage waveform and synchronously obtains the angular frequency of this sinusoidal AC voltage. and amplitude and dynamically adjust This achieves power factor correction. The control strategy employs a hybrid modulation control of pulse width modulation (PWM) and phase-shifted modulation (PSM). PWM primarily adjusts the duty cycle D of the primary-side interleaved parallel circuit to achieve energy distribution between the photovoltaic system and the battery; PSM adjusts the duty cycle D by... Compared to relocation The two work together to improve the system's energy management flexibility and operational efficiency.
[0044] according to Figure 3 This allows us to obtain the leakage inductance current during each time period within a complete operating cycle of the converter in steady state. The expression:
[0045] From capacitor The balance of ampere-seconds indicates that... The expression:
[0046] By measuring the voltage at the midpoint of the primary side bridge arm of the transformer and leakage current Integrating the product over one switching cycle yields the system output power. expression:
[0047] To achieve the original edge - The soft switching of all switching transistors must meet the following requirements:
[0048] It can be seen that, Large enough to achieve the original edge - Soft switching for all switching transistors, but with specific... and The combination of these elements minimizes the inductor current stress. (Definition) Normalized output power ( and ), Normalized inductor current stress ( and ), The expected nominal output power will be used in the evaluation function. Represented as:
[0049] In order to make To minimize inductor current stress, the following condition must be met:
[0050] Therefore, it can be deduced that the third high-frequency switching transistor and the sixth high-frequency switching transistor The inward shift satisfies the following relationship: , in, The third high-frequency switching transistor and the sixth high-frequency switching transistor Compared to the inward shift, Compared to the outward movement of the primary and secondary windings of the high-frequency transformer, The ratio of the number of turns in the secondary winding to the number of turns in the primary winding of the high-frequency transformer. This refers to the input voltage at the battery port. Let be the amplitude of the sinusoidal alternating voltage. Let be the angular frequency of the sinusoidal AC voltage.
[0051] Please refer to Figure 7 This illustration shows a system schematic of a power supply system provided in one embodiment of this application. The power supply system includes, as shown in the diagram... Figure 2 The multi-port converter shown is designed for optical storage systems. Figure 1 Compared to the conventional modular DC-DC-AC power supply system shown, the output voltage and output current of each photovoltaic array only need to pass through a three-port single-stage DC-DC-AC converter, i.e., the embodiment of this application. Figure 2 The multi-port converter shown is designed for optical storage systems. Compared to... Figure 1Each photovoltaic array requires at least two two-port DC-DC converters and two two-port DC-AC inverters. The embodiments of this application can realize the reuse of DC-DC converters, improve system integration, thereby reducing system size and cost.
[0052] It is understood that the specific examples in this application are only intended to help those skilled in the art better understand the implementation methods of this application, and are not intended to limit the scope of the invention.
[0053] It is understood that the various implementation methods described in this application can be implemented individually or in combination, and the implementation methods in this application are not limited in this respect.
[0054] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.
[0055] The above are merely specific embodiments of this application, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this invention should be determined by the scope of the claims.
Claims
1. A multi-port converter for photovoltaic-storage systems, characterized in that, The multi-port converter includes a first high-frequency switch, a second high-frequency switch, a third high-frequency switch, a fourth high-frequency switch, a fifth high-frequency switch, a sixth high-frequency switch, a seventh high-frequency switch, an eighth high-frequency switch, a ninth high-frequency switch, a tenth high-frequency switch, a first inductor, a second inductor, and a high-frequency transformer; wherein: Energy is transmitted between the photovoltaic port and the battery port through a two-phase interleaved parallel boost circuit. The two-phase interleaved parallel boost circuit includes a first high-frequency switch, a second high-frequency switch, a third high-frequency switch, a fourth high-frequency switch, a fifth high-frequency switch, a sixth high-frequency switch, a first inductor, and a second inductor. The battery port transmits energy to the AC bus port through a dual active bridge circuit. The dual active bridge circuit includes two full-bridge circuits and the high-frequency transformer. One of the full-bridge circuits includes a first high-frequency switch, a second high-frequency switch, a third high-frequency switch, a fourth high-frequency switch, a fifth high-frequency switch, and a sixth high-frequency switch. The other full-bridge circuit includes a seventh high-frequency switch, an eighth high-frequency switch, a ninth high-frequency switch, and a tenth high-frequency switch. One of the full-bridge circuits is connected to the primary winding of the high-frequency transformer, and the other full-bridge circuit is connected to the secondary winding of the high-frequency transformer.
2. The multiport converter according to claim 1, characterized in that, The positive terminal of the battery port is connected to the drain of the first high-frequency switching transistor and the fourth high-frequency switching transistor. The source of the first high-frequency switching transistor is connected to the drain of the second high-frequency switching transistor and one end of the first inductor. The source of the fourth high-frequency switching transistor is connected to the drain of the fifth high-frequency switching transistor and one end of the second inductor. The source of the second high-frequency switching transistor and the drain of the third high-frequency switching transistor are connected to one end of the primary winding of the high-frequency transformer. The source of the fifth high-frequency switching transistor and the drain of the sixth high-frequency switching transistor are connected to the other end of the primary winding of the high-frequency transformer. The positive terminal of the photovoltaic port is connected to the other end of the first inductor and the second inductor. The negative terminals of the battery port and the photovoltaic port are connected to the source of the third high-frequency switching transistor and the source of the sixth high-frequency switching transistor.
3. The multi-port converter according to claim 2, characterized in that, One of the full-bridge circuits further includes a leakage inductance and a capacitor. The source of the second high-frequency switch and the drain of the third high-frequency switch are connected to one end of the primary winding of the high-frequency transformer through the leakage inductance. The source of the fifth high-frequency switch and the drain of the sixth high-frequency switch are connected to the other end of the primary winding of the high-frequency transformer through the capacitor.
4. The multiport converter according to any one of claims 1-3, characterized in that, In the two-phase interleaved parallel boost circuit, the first high-frequency switch and the high-frequency switch consisting of the second and third high-frequency switches are complementary in conduction, and the fourth high-frequency switch and the high-frequency switch consisting of the fifth and sixth high-frequency switches are complementary in conduction. In the dual active bridge circuit, the high-frequency switch consisting of the first high-frequency switch and the second high-frequency switch is complementary to the third high-frequency switch, and the high-frequency switch consisting of the fourth high-frequency switch and the fifth high-frequency switch is complementary to the sixth high-frequency switch.
5. The multiport converter according to claim 1, characterized in that, The positive terminal of the AC bus port is connected to the drain of the seventh and ninth high-frequency switching transistors. The source of the seventh and eighth high-frequency switching transistors is connected to one end of the secondary winding of the high-frequency transformer. The source of the ninth and tenth high-frequency switching transistors is connected to the other end of the secondary winding of the high-frequency transformer. The negative terminal of the AC bus port is connected to the source of the eighth and tenth high-frequency switching transistors.
6. The multiport converter according to claim 5, characterized in that, The multi-port converter further includes a third inductor, a fourth inductor, a first power frequency switch, and a second power frequency switch. The positive terminal of the AC bus port is connected to the drain of the seventh high-frequency switch, the ninth high-frequency switch, and the first power frequency switch. The source of the first power frequency switch and the drain of the second power frequency switch are connected to the other ends of the third inductor and the fourth inductor. The negative terminal of the AC bus port is connected to the source of the eighth high-frequency switch, the tenth high-frequency switch, and the second power frequency switch. The source of the seventh high-frequency switch and the drain of the eighth high-frequency switch are connected to the secondary winding of the high-frequency transformer and one end of the third inductor. The source of the ninth high-frequency switch and the drain of the tenth high-frequency switch are connected to the other end of the secondary winding of the high-frequency transformer and one end of the fourth inductor.
7. The multi-port converter according to claim 6, characterized in that, The seventh and eighth high-frequency switching transistors are complementary in conduction, and the ninth and tenth high-frequency switching transistors are complementary in conduction.
8. The multiport converter according to claim 6, characterized in that, The first and second power frequency switching transistors are complementary in conduction and alternately conduction within the power frequency cycle, causing the polarity of the output voltage to alternately reverse, thereby forming a sinusoidal AC voltage.
9. The multiport converter according to claim 8, characterized in that, The inward shift of the third high-frequency switch and the sixth high-frequency switch satisfies the following relationship: ， in, Compared to the inward shift of the third high-frequency switch and the sixth high-frequency switch, Compared to the outward movement of the primary and secondary windings of the high-frequency transformer, The ratio of the number of turns in the secondary winding to the number of turns in the primary winding of the high-frequency transformer. The input voltage at the battery port is [value]. Let be the amplitude of the sinusoidal AC voltage. Let be the angular frequency of the sinusoidal AC voltage.
10. A power supply system, characterized in that, The power supply system includes a multiport converter as described in any one of claims 1-9.