A novel tapless resonant push-pull photovoltaic energy storage inverter topology

Abstract

A novel tapless resonant push-pull photovoltaic energy storage inverter topology is disclosed, relating to the field of energy storage system topology control technology, specifically a novel tapless resonant push-pull photovoltaic energy storage inverter topology. It includes a photovoltaic boost MPPT circuit, a DC-AC bidirectional inverter circuit, and a battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit. The photovoltaic boost MPPT circuit is used to increase the DC voltage of the photovoltaic panels and perform maximum power point tracking control. The DC-AC bidirectional inverter circuit performs bidirectional DC-to-AC conversion through three independent T-type three-level circuits, each independently controlled, with low harmonic output current. The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit includes a tapless transformer and a push-pull circuit. Through innovative tapless resonant push-pull circuit, dual-transformer interleaved control technology, and three-level inverter circuit design, it achieves efficient power conversion, optimized battery charge and discharge management, and reduced high-frequency ripple and electromagnetic interference, thereby improving the overall efficiency, stability, and reliability of the photovoltaic energy storage system.

Description

Technical Field

[0001] This invention relates to the field of energy storage system topology control technology, and in particular to a novel tapless resonant push-pull photovoltaic energy storage inverter topology. Background Technology

[0002] With the rapid development of new energy sources, the demand for power and the application of new energy storage systems are gradually increasing. In particular, solar energy storage systems are a renewable energy source with a wide range of applications and a very fast development speed. In the next few years, with the rapid increase in the computing power demand for large-scale AI data, there will be a large market space for electricity demand. However, with the continuous improvement of power supply technology, the demand for electricity will be limited.

[0003] Existing single-phase and three-phase energy storage inverter technologies still suffer from the following problems: Traditional single-phase energy storage systems are complex to control and have a large number of power transistors, resulting in high costs; they are also less efficient, especially in high-power applications, where overload problems and high harmonics may occur. Traditional three-phase energy storage systems use a three-arm I-type topology or a T-type three-level topology, which is complex and difficult to control; they also have high power losses and high-frequency ripple, making it difficult to meet the requirements for high-efficiency energy conversion. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings and deficiencies of existing technologies by providing a novel tapless resonant push-pull photovoltaic energy storage inverter topology. Through innovative tapless resonant push-pull circuit, dual transformer interleaved control technology, and three-level inverter circuit design, it achieves efficient power conversion, optimized battery charge and discharge management, and reduced high-frequency ripple and electromagnetic interference, thereby improving the overall efficiency, stability, and reliability of the photovoltaic energy storage system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: it includes a photovoltaic boost MPPT circuit 10, a DC-AC bidirectional inverter circuit 20, and a battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30. The photovoltaic boost MPPT circuit 10 is used to increase the DC voltage of the photovoltaic panel and perform maximum power point tracking control. The DC-AC bidirectional inverter circuit 20 performs bidirectional DC-to-AC conversion through three independent T-type three-level circuits, each of which is independently controlled, resulting in low harmonic output current. The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30 includes a tapless transformer and a push-pull circuit. It has a zero-current shutdown (ZCS) function, optimizes battery charging and discharging efficiency, reduces high-frequency ripple, and improves system efficiency.

[0006] The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30 includes a dual-transformer staggered configuration. By staggering the operating phase of the dual transformers, the high-frequency ripple of the battery bus and the DC bus ripple are further reduced, thereby improving the electromagnetic compatibility (EMI) and overall system efficiency.

[0007] The DC-AC bidirectional inverter circuit 20 adopts a T-type three-level circuit. Each circuit includes an independent control interface and an inductor filter circuit to ensure the stability and reliability of the power supply and reduce the harmonic rate of the output current.

[0008] The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30 adopts a dual-transformer interleaved operating mode, which effectively reduces the ripple of the battery bus and high-voltage DC bus on the battery side, further optimizing the system's performance and stability.

[0009] The photovoltaic boost MPPT circuit 10 adopts a 1000V high-voltage system. Compared with the traditional 600V system, it improves the oversizing capability by about 40%.

[0010] The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30 includes a dual-transformer interleaved operating mode. This mode ensures smooth voltage conversion during battery charging and discharging, reduces high-frequency ripple on the battery side, and improves battery life. Interleaved control technology optimizes ripple and electromagnetic interference during power conversion by adjusting the operating phases of different transformers, further enhancing the overall efficiency and performance of the system.

[0011] The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30 is equipped with a battery-side charging and discharging unit 301. The battery-side charging and discharging unit 301 is a battery voltage input of 72V, 48V or 24V. It uses a transformer for high-frequency isolation conversion and outputs a high-voltage DC unit through an LLC resonant circuit, which has bidirectional energy conversion capability.

[0012] The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30 is equipped with a three-phase high-voltage output terminal 301. The output of the three-phase high-voltage output terminal 301 is 380V, 400V or 415V three-phase AC power, which can be connected to the power grid or used as a backup power output for the energy storage system. When the power grid fails, the energy storage system can provide power as a backup power source.

[0013] The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30 is equipped with a single high-voltage output terminal 302, which outputs 220V single-phase AC power. The DC power after voltage conversion is converted into AC power by a DC-AC inverter circuit and output to the power grid or load.

[0014] The DC-AC bidirectional inverter circuit 20 provides low-harmonic, high-efficiency AC output through an interleaved three-level inverter bridge architecture 201, making it suitable for high-power applications.

[0015] The working principle of this invention is as follows: The DC current generated by the photovoltaic panels (PV1, PV2) passes through the photovoltaic boost MPPT circuit 10. The main function of this circuit is to increase the DC voltage of the photovoltaic panels and, through a maximum power point tracking (MPPT) control algorithm, ensure that the output power of the photovoltaic panels is always maintained at its maximum value. The current first flows into the boost circuits 7A and 7B, and then, after being boosted, is output to subsequent circuits (such as the DC-AC inverter circuit and the battery-side DC-DC circuit). In this process, the switching transistors of the boost circuit play a role in controlling the voltage and current, ensuring the optimal operating state of the photovoltaic system.

[0016] The DC-AC bidirectional inverter circuit 20 converts direct current (DC) from the photovoltaic panel and battery system into alternating current (AC) via three independent T-type three-level circuits. In discharge mode (battery powered), the inverter converts DC to AC and outputs it to the grid or load. In charging mode (grid charging the battery), it converts AC to DC and feeds the energy into the battery system. Inductor filtering circuits (labeled L1 and L2) and independent control interfaces ensure low harmonic distortion in the output AC.

[0017] The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30 controls the charging and discharging of the battery through a tapless transformer and push-pull circuit design. This circuit features zero-current shutdown (ZCS) and employs an interleaved control dual-transformer structure to further optimize the battery charging and discharging process. During battery charging, DC current is converted to a suitable voltage for battery charging via transformer T1 (marked as 9A, 9B) and the LLC resonant circuit. During battery discharging, the DC current in the battery is converted to high-voltage DC current via transformer T2 (marked as 15A, 15B) and the LLC2 circuit, and then output to the power grid or load through a DC-AC inverter circuit.

[0018] The three-phase high-voltage output terminal 302 on the battery side provides 380V, 400V, or 415V three-phase AC power, while the single-phase high-voltage output terminal can also provide 220V AC power. In this case, the high-frequency isolation conversion on the battery side, through the control of an LLC resonant circuit and an interleaved transformer, optimizes the stability of the output voltage and reduces high-frequency ripple on the battery bus. The output current is converted to AC power through a three-level inverter bridge architecture 201, which can then be connected to the grid or used as a backup power source for an energy storage system.

[0019] By adopting the above technical solution, the beneficial effects of this invention are as follows: By employing a tapless transformer and push-pull circuit design, this invention can reduce switching losses and improve the efficiency of the battery charging and discharging process. Through the tapless transformer design, current transmission losses are reduced, and the battery charging and discharging process is optimized, thereby significantly improving the overall energy conversion efficiency of the system.

[0020] By employing a dual-transformer interleaved operating mode, the ripple on the battery bus and the high-voltage DC bus on the battery side is effectively reduced. The interleaved control technology optimizes ripple and electromagnetic interference (EMI) during power conversion by adjusting the operating phases of different transformers. This design not only improves system stability but also reduces electromagnetic interference between the battery and the grid, making the system more environmentally friendly and compliant with international electromagnetic compatibility standards.

[0021] The three-level T-type inverter circuit and independent control interface in this invention make the DC-AC inverter process more stable. Each circuit, through independent control and filtering, ensures the stability and reliability of the power supply while reducing the harmonic rate of the output current. This design maintains low output current harmonics even under load changes, optimizing power quality and improving system stability.

[0022] Dual-transformer interleaved control and smooth voltage conversion effectively reduce high-frequency ripple on the battery bus and improve battery charging and discharging efficiency. Precise voltage control prevents overcharging and over-discharging during charging and discharging, thereby extending battery life and enhancing the long-term stability of the energy storage system.

[0023] Through innovative circuit design, such as interleaved control technology and high-frequency isolation transformers, this invention effectively simplifies the system's control circuit and structural design. Using fewer power transistors and a simpler control algorithm reduces system complexity and cost. The system's high-efficiency energy conversion and stability further reduce overall costs, thereby improving customer economic benefits.

[0024] The combined effects of the technologies of this invention give the photovoltaic energy storage inverter system significant advantages in terms of high efficiency, stability, environmental friendliness, adaptability, and cost-effectiveness. It meets the needs of energy storage systems of different scales and has broad application prospects. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention 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.

[0026] Figure 1 This is a schematic diagram of the circuit structure of the present invention.

[0027] Figure labeling: 10 photovoltaic boost MPPT circuit, 20 DC-AC bidirectional inverter circuit, 30 battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit, 301 three-phase high-voltage output terminal, 302 single-phase high-voltage output terminal, 201 three-level inverter bridge architecture. Detailed Implementation

[0028] See Figure 1 As shown, the technical solution adopted in this specific embodiment is as follows: The photovoltaic energy storage inverter system of this specific embodiment includes three main circuit modules: a photovoltaic boost MPPT circuit, a DC-AC bidirectional inverter circuit, and a battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit. Each part of the system operation process has been carefully designed to ensure efficient energy conversion and power management.

[0029] First, the DC current generated by the photovoltaic panels (PV1 and PV2) is boosted by a photovoltaic boost MPPT circuit (labeled 10) and subjected to maximum power point tracking (MPPT) control. This circuit optimizes the output power of the photovoltaic panels, ensuring the system always operates at its maximum power point. The low voltage of the photovoltaic panels is then boosted by boost circuits (7A and 7B) to a suitable voltage for subsequent circuits, providing the energy to the DC-AC bidirectional inverter circuit and the battery-side DC-DC circuit for further power conversion and storage. Next, the DC-AC bidirectional inverter circuit 20 converts the DC current from the photovoltaic panels or batteries into AC current, or vice versa, for power storage. This circuit uses three independent T-type three-level circuits (labeled 5A, 6A, 5B, and 6B) with independent control interfaces and inductor filtering circuits to ensure low harmonics and stability of the output current. In discharge mode, the DC current stored in the battery is converted to AC current by the inverter circuit and output to the grid or load; in charging mode, the AC current from the grid is converted to DC current by the inverter circuit to charge the battery.

[0030] The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit 30 is responsible for matching and converting the battery voltage with the DC bus voltage. This circuit uses a tapless transformer and push-pull circuit, combined with an LLC resonant circuit for high-frequency isolation conversion. It also features zero-current shutdown (ZCS) to reduce switching losses and optimize battery charging and discharging efficiency. During battery charging, the DC power is converted to a suitable charging voltage for the battery via transformers (labeled T1 and T2) and the LLC resonant circuit. During battery discharging, the battery's DC power is converted to high-voltage DC power via the same circuit, and then converted to AC power via a DC-AC inverter circuit for output to the grid or load.

[0031] The battery-side DC-DC circuit employs dual-transformer interleaved control technology. By adjusting the operating phases of different transformers, it further reduces high-frequency ripple on the battery bus and DC bus. Interleaved control makes the power conversion process smoother and reduces electromagnetic interference (EMI), thereby improving the system's efficiency and stability.

[0032] The system's three-phase high-voltage output terminal 301 provides 380V, 400V, or 415V three-phase AC power, which can be connected to the power grid or used as a backup power source for an energy storage system. When the power grid fails, the energy storage system can continue to supply power to the load as a backup power source. In addition, the system can also be equipped with a single-phase high-voltage output terminal 302, which outputs 220V single-phase AC power, suitable for low-power loads. DC power is converted to AC power via a DC-AC inverter circuit and finally output to the power grid or load.

[0033] By using a three-level inverter bridge architecture 201 and interleaved control technology, the DC-AC bidirectional inverter circuit of this specific embodiment can provide low-harmonic, high-efficiency AC output, making it particularly suitable for high-power applications. Each circuit module is designed with high efficiency and stability in power conversion in mind, ensuring that the entire system can operate stably in various application scenarios.

[0034] This specific implementation provides a stable, reliable, and efficient photovoltaic energy storage inverter system through high-efficiency power conversion and energy storage management technologies. The modules work collaboratively to maximize system power output and optimize battery charging and discharging efficiency. Particularly in the design of the battery-side DC-DC circuit, interleaved control technology and a tapless transformer design further reduce high-frequency ripple and improve the overall system performance. This system is suitable for residential, commercial, and industrial energy storage systems and has broad application prospects.

[0035] This specific implementation achieves efficient power conversion, optimized battery charge and discharge management, and reduced high-frequency ripple and electromagnetic interference through innovative tapless resonant push-pull circuit, dual-transformer interleaved control technology, and three-level inverter circuit design, thereby improving the overall efficiency, stability, and reliability of the photovoltaic energy storage system.

[0036] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A novel tapless resonant push-pull photovoltaic energy storage inverter topology, characterized in that: It includes a photovoltaic boost MPPT circuit (10), a DC-AC bidirectional inverter circuit (20), and a battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit (30). The photovoltaic boost MPPT circuit (10) is used to increase the DC voltage of the photovoltaic panel and perform maximum power point tracking control. The DC-AC bidirectional inverter circuit (20) performs bidirectional conversion from DC to AC through three independent T-type three-level circuits. Each circuit is independently controlled and the output current has low harmonics. The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit (30) includes a tapless transformer and a push-pull circuit.

2. The novel tapless resonant push-pull photovoltaic energy storage inverter topology according to claim 1, characterized in that: The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit (30) includes a dual-transformer staggered configuration. By staggering the working phase of the dual transformers, the high-frequency ripple of the battery bus and the DC bus ripple are further reduced, thereby improving the electromagnetic compatibility and overall efficiency of the system.

3. The novel tapless resonant push-pull photovoltaic energy storage inverter topology according to claim 1, characterized in that: The DC-AC bidirectional inverter circuit (20) adopts a T-type three-level circuit. Each circuit includes an independent control interface and an inductor filter circuit to ensure the stability and reliability of the power supply and reduce the harmonic rate of the output current.

4. The novel tapless resonant push-pull photovoltaic energy storage inverter topology according to claim 1, characterized in that: The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit (30) adopts a dual-transformer interleaved working mode, which effectively reduces the ripple of the battery bus and the high-voltage DC bus on the battery side, further optimizing the system's performance and stability.

5. The novel tapless resonant push-pull photovoltaic energy storage inverter topology according to claim 1, characterized in that: The photovoltaic boost MPPT circuit (10) adopts a 1)00V high voltage system.

6. The novel tapless resonant push-pull photovoltaic energy storage inverter topology according to claim 1, characterized in that: The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit (30) includes a dual-transformer interleaved operating mode. The dual-transformer interleaved operating mode can ensure the smooth voltage conversion during battery charging and discharging, reduce high-frequency ripple on the battery side, and improve battery life.

7. The novel tapless resonant push-pull photovoltaic energy storage inverter topology according to claim 1, characterized in that: The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit (30) is equipped with a battery-side charging and discharging unit (301). The battery-side charging and discharging unit (30) is a battery voltage input of 72V, 48V or 24V. It uses a transformer for high-frequency isolation conversion and outputs a high-voltage DC unit through an LLC resonant circuit, which has bidirectional energy conversion capability.

8. The novel tapless resonant push-pull photovoltaic energy storage inverter topology according to claim 1, characterized in that: The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit (30) is equipped with a three-phase high-voltage output terminal (301). The output of the three-phase high-voltage output terminal (301) is 380V, 400V or 415V three-phase AC power, which can be connected to the power grid or used as a backup power output for the energy storage system. When the power grid fails, the energy storage system can provide power as a backup power source.

9. The novel tapless resonant push-pull photovoltaic energy storage inverter topology according to claim 1, characterized in that: The battery-side DC-DC tapless resonant push-pull bidirectional isolated charging circuit (30) is provided with a single high-voltage output terminal (302), which outputs 220V single-phase AC power.

10. The novel tapless resonant push-pull photovoltaic energy storage inverter topology according to claim 1, characterized in that: The DC-AC bidirectional inverter circuit (20) provides low-harmonic, high-efficiency AC output through an interleaved three-level inverter bridge architecture (201), making it suitable for high-power applications.

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