A multi-port high-gain converter for optical storage systems

Abstract

This invention relates to a multi-port high-gain converter for a photovoltaic-energy storage system. A photovoltaic cell, a third switch, a second switch, and a second inductor are connected in series, with the first and third switches connected in parallel. The first switch is connected in series with a first capacitor and then in parallel with the third switch. One end of the first inductor is connected between the photovoltaic cell and the second inductor, and the other end is connected between the first switch and the first capacitor. A diode, a second capacitor, a third inductor, an energy storage battery, and a third capacitor are connected in series and in parallel with the second and third switches. The positive terminal of the diode is connected to the second capacitor, and the negative terminal is connected to the third capacitor. A fourth switch is connected in parallel with the third inductor and the energy storage battery. The fourth inductor is connected in parallel with the second capacitor, the third inductor, and the energy storage battery. The output capacitor is connected in series with a fifth switch and then in parallel with the diode, the second capacitor, the third inductor, and the energy storage battery. This device constructs a multi-modal parallel DC-side energy storage system, enabling bidirectional energy flow within the photovoltaic-energy storage system and ensuring highly reliable power supply.

Description

Technical Field

[0001] This application relates to the field of electronic devices, and in particular to a multi-port high-gain converter for optical storage systems. Background Technology

[0002] With a high proportion of new energy equipment being integrated into the power system, photovoltaic (PV) and energy storage systems can provide reliable power to users during peak energy consumption periods, and their applications are widespread. They can function not only as independent systems supplying power to areas without main grid support, but also as backup power sources to make urban power grids more resilient. To achieve this goal, it is necessary to optimize system efficiency and performance through research on high-efficiency PV-energy storage converters. Since new energy power generation is significantly affected by the environment and has a relatively low output voltage level, a boost converter needs to be connected at the output port for power conversion and voltage boosting. Considering that this scenario often involves multiple input sources such as power generation devices and energy storage batteries, multi-input port (MIPC) DC-DC converters have received widespread attention. High-gain MPC converters can reduce total design costs and improve system reliability. MPC DC-DC converters are becoming increasingly popular in sustainable energy applications that require the integration of multiple power sources. Compared to single-input port converters, high-gain MPC DC-DC converters can reduce design costs and improve reliability.

[0003] like Figure 1 The diagram shows an existing multi-input port DC-DC converter, comprising: a photovoltaic cell, inductors L1 and L2, power switches Q1 and Q2, capacitors C1 and C2, diode D1, and an energy storage battery. The photovoltaic cell, inductor L1, power switch Q2, diode D1, and output terminal V0 are connected in series. The photovoltaic cell is connected to inductor L1 at node A1, and then connected in parallel with power switch Q1 at nodes A2 and B1. Inductor L1 is connected to power switches Q1 and Q2 at node A2. The energy storage battery Vbat is connected in parallel with capacitor C2 at nodes B2 and B3, then connected in series with inductor L2 at node B2, and then connected in parallel with diode D1 at nodes A3 and A4. Capacitor C1 is connected in parallel with output terminal V0 at nodes A5 and B4.

[0004] Multi-input DC-DC converters are becoming increasingly popular in sustainable energy applications that require the integration of multiple power supplies; however, existing technologies have some limitations, such as:

[0005] 1. Due to the need to meet the high voltage gain requirement, the power switches and diodes in the above converter will be subjected to large voltage stress, thus requiring high power rated devices;

[0006] 2. Most multi-input port DC-DC converters have high output voltage ripple. Although there are existing technical solutions to address this issue, they reduce the voltage gain of the converter, which limits its practical application in industrial settings.

[0007] Especially for large-scale photovoltaic-storage parallel systems, the structure and control strategies of the power system are becoming increasingly complex as new energy generation units, loads, and energy storage units are continuously connected. Developing multi-port high-gain converters to form multi-modal energy storage DC-side parallel configurations is an important component of future intelligent power distribution systems, and is of great significance for promoting energy conservation and emission reduction and achieving sustainable energy development. Summary of the Invention

[0008] This application provides a multi-port high-gain converter for optical storage systems, which can solve at least one of the above problems and provide greater gain with the same number of devices.

[0009] To achieve the above objectives, embodiments of this application propose a multi-port high-gain converter for an optical storage system; comprising:

[0010] Photovoltaic cells, energy storage batteries, first inductor, second inductor, third inductor, fourth inductor, first capacitor, second capacitor, third capacitor, output capacitor, first switch, second switch, third switch, fourth switch, fifth switch, diode.

[0011] In this configuration, the photovoltaic cell, the third switch, the second switch, and the second inductor are connected in series, and the first switch and the third switch are connected in parallel. The first switch and the first capacitor are connected in series and then in parallel with the third switch. One end of the first inductor is connected between the photovoltaic cell and the second inductor, and the other end is connected between the first switch and the first capacitor.

[0012] The diode, the second capacitor, the third inductor, the energy storage battery, and the third capacitor are connected in series and in parallel with the second and third switches; the positive terminal of the diode is connected to the second capacitor and the negative terminal is connected to the third capacitor.

[0013] The fourth switch is connected in parallel with the third inductor and the energy storage battery; the fourth inductor is connected in parallel with the second capacitor, the third inductor and the energy storage battery; the output capacitor is connected in series with the fifth switch and then in parallel with the diode, the second capacitor, the third inductor and the energy storage battery.

[0014] The first, second, third, fourth, and fifth switches mentioned above all employ power switches capable of bidirectional power flow, particularly insulated gate bipolar transistors (IGBTs).

[0015] Among them, the output port voltage V 0The relationship between the supply voltage of the photovoltaic cell and the supply voltage of the energy storage battery is expressed as follows:

[0016] (1)

[0017] In equation (1), V 0 Indicates the output port voltage. V 1 This indicates the supply voltage of the photovoltaic cell. V 2 This indicates the supply voltage of the energy storage battery, where V 1 Provided by photovoltaic cells, specifically the output port voltage of the photovoltaic cells. V 2 The voltage is supplied by the energy storage battery, which is the output port voltage of the energy storage battery, ignoring line losses. d 1 Indicates a duty cycle of 1. d 2 This indicates a duty cycle of 2.

[0018] The first, second, and fourth switches are in the ON state, while the third, fifth, and diodes are in the OFF state. The photovoltaic cell and energy storage battery charge the first and second inductors to store energy. The energy storage battery and the second capacitor discharge to the third and fourth inductors. The output capacitor is in the discharge state.

[0019] The third, fourth, and fifth switches are off, and the diode is on. The energy storage battery and the third inductor charge the second capacitor, and the energy storage battery, the third inductor, and the fourth inductor charge the third capacitor simultaneously. The photovoltaic cell charges the first inductor, and the energy storage battery charges the second inductor.

[0020] In this configuration, the first switch, the second switch, and the diode are off, while the fourth, third, and fifth switches are on. At this time, the photovoltaic cell, the second inductor, and the third capacitor discharge to the load and the output capacitor through the fifth switch.

[0021] To achieve the above objectives, this application also proposes a control method for a multi-port high-gain converter in a photovoltaic-storage system. Developing a multi-port high-gain converter facilitates stable control of the DC bus voltage and ensures stable system operation. The method includes at least one of the following steps:

[0022] The first, second, and fourth switches are in the ON state, while the third, fifth, and diodes are in the OFF state. The photovoltaic cell and energy storage battery charge the first and second inductors to store energy. The energy storage battery and the second capacitor discharge to the third and fourth inductors. The output capacitor is in the discharge state.

[0023] The third, fourth, and fifth switches are off, and the diode is on. The energy storage battery and the third inductor charge the second capacitor, and the energy storage battery, the third inductor, and the fourth inductor charge the third capacitor simultaneously. The photovoltaic cell charges the first inductor, and the energy storage battery charges the second inductor.

[0024] or

[0025] In this configuration, the first switch, the second switch, and the diode are off, while the fourth, third, and fifth switches are on. At this time, the photovoltaic cell, the second inductor, and the third capacitor discharge to the load and the output capacitor through the fifth switch.

[0026] The beneficial effects of the above technical solution in this application are as follows:

[0027] This application discloses a modular high-voltage-gain multi-input port DC-DC converter topology with continuous input current. Compared with existing technologies, the topology proposed in this application can provide greater gain with the same number of devices. In other words, the topology proposed in this application uses fewer devices to achieve the same voltage gain.

[0028] Another advantage of this application is that when a higher converter output voltage level is required, the reverse voltage on the switches and diodes does not exceed the upper limit. Furthermore, this topology has good scalability, allowing for the expansion of input ports while increasing the system's voltage gain. The multi-port high-gain converter proposed in this application can be used to construct multi-modal energy storage DC-side parallel systems. Based on this invention, bidirectional energy flow in photovoltaic-energy storage systems can be realized, allowing parallel connection with existing AC / DC microgrids or distribution networks, and effectively isolating AC disturbances or faults to ensure highly reliable power supply to loads within the DC system.

[0029] Meanwhile, this application also provides a control method for an energy storage conversion device. By developing a multi-port high-gain converter, the smooth control of the DC bus voltage and the stable and reliable operation of the system can be achieved. Attached Figure Description

[0030] Figure 1 This is an existing multi-input port DC-DC converter;

[0031] Figure 2 This is a schematic diagram of the circuit structure of an embodiment of this application;

[0032] Figure 3 for Figure 2 The circuit diagram is equivalent to the circuit in mode 1.

[0033] Figure 4 for Figure 2The equivalent circuit diagram of the circuit operating in mode two;

[0034] Figure 5 for Figure 2 The equivalent circuit diagram of the circuit operating in mode three;

[0035] Figure 6 for Figure 2 The circuit diagram is an extension circuit diagram when the circuit is applied to multiple input ports. Detailed Implementation

[0036] To make the technical problems, technical solutions and advantages of this application clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0037] like Figure 2 As shown, an embodiment of this application proposes a multi-port high-gain converter for an optical storage system, comprising:

[0038] Multi-input port DC-DC converter topology as follows Figure 2 As shown, the topology includes a photovoltaic cell V1, an energy storage cell V2, four inductors: the first inductor, the second inductor, the third inductor, and the fourth inductor; hereinafter referred to as inductor L1, inductor L2, inductor L3, and inductor L4, respectively; four capacitors: the first capacitor, the second capacitor, the third capacitor, and the output capacitor; hereinafter referred to as capacitor C1, capacitor C2, capacitor C3, and capacitor Co, respectively; five switches: the first switch, the second switch, the third switch, the fourth switch, and the fifth switch; hereinafter referred to as switch Q1, switch Q2, switch Q3, switch Q4, and switch Q5, respectively; and a diode D1.

[0039] For a clearer explanation, such as Figure 2 Each connection node is also numbered, as shown. Figure 2As shown, the input port (i.e., photovoltaic cell V1) is connected to nodes B1 and B7. Inductor L1 is located between nodes B1 and B2, inductor L2 between nodes A1 and B1, inductor L3 between nodes B5 and B6, and inductor L4 between nodes B4 and B7. Capacitor C1 is located between nodes B2 and B3, capacitor C2 between nodes B4 and B5, capacitor C3 between nodes A1 and A2, and capacitor Co between nodes A3 and B7. Diode D1 is located between nodes A2 and B4. Switch Q1 is located between nodes B2 and B7, switch Q2 between nodes A1 and B3, switch Q3 between nodes B3 and B7, switch Q4 between nodes B5 and B7, and switch Q5 between nodes A2 and A3. The input port (energy storage cell V2) is connected to nodes B6 and B7 and is connected in series with inductor L3. The final system output ports are nodes A3 and B7, with node A3 serving as the positive output port and node B7 as the negative output port. Switches Q1, Q2, Q3, Q4, and Q5 are IGBT switching transistors.

[0040] In some embodiments, to achieve bidirectional power flow, switches Q1, Q2, Q3, Q4, and Q5 are all selected as bidirectional power switches. The system has two output ports: the output port of photovoltaic cell V1 and the output port of energy storage battery V2. The driving waveforms of switches Q1 and Q2 are identical, while the driving waveforms of switches Q3 and Q5 are complementary to those of switches Q1 and Q2. According to the conduction mechanism, only two duty cycle control signals, duty cycle 1 and duty cycle 2, are needed to control switches Q1 and Q4 respectively. Therefore, according to... Figure 2 The circuit diagram shown illustrates the state combinations of the five switches and diodes, allowing the multi-input port DC-DC converter to operate in multiple modes. For example,... Figure 3 , Figure 4 , Figure 5 The diagram shows the three operating modes of the system:

[0041] Mode 1: Switches Q1, Q2, and Q4 are in the ON state, while switches Q3, Q5, and diode D1 are in the OFF state. The circuit in the OFF state is not connected; therefore, the circuits corresponding to switches Q3, Q5, and diode D1 are automatically disconnected. Figure 2 After deletion, it forms the following Figure 3 The circuit structure is shown. In this case, inductors L1 and L2 store energy, which is charged by photovoltaic cell V1 and energy storage battery V2, respectively. Simultaneously, energy storage battery V2 and capacitor C2 discharge to inductors L3 and L4; the output capacitor Co is in a discharging state.

[0042] Mode 2: Switches Q3, Q4, and Q5 are in the off state. The circuit in the off state is not connected, and the circuits corresponding to switches Q3, Q4, and Q5 are automatically... Figure 2 After deletion, it forms the following Figure 4 In the circuit structure shown, diode D1 is in the ON state. Energy storage battery V2 and inductor L3 charge capacitor C2, while energy storage battery V2, inductor L3, and inductor L4 simultaneously charge capacitor C3. Photovoltaic cell V1 charges inductor L1, and energy storage battery V2 charges inductor L2.

[0043] Mode 3: Switches Q1 and Q2, and diode D1 are in the off state. The circuit in the off state is not connected, and the circuits corresponding to switches Q1, Q2, and diode D1 are automatically... Figure 2 After deletion, it forms the following Figure 5 In the circuit structure shown, switches Q4, Q3, and Q5 are in the ON state. At this time, the photovoltaic cell V1, inductor L2, and capacitor C3 discharge to the load and output capacitor Co through switch Q5.

[0044] The relationship between the output port voltage V0 and the supply voltage of the photovoltaic cell and the supply voltage of the energy storage battery is expressed by the following formula:

[0045] (1)

[0046] In equation (1), V 0 Indicates the output port voltage, where V 1 Provided by photovoltaic cell V1, that is, the output port voltage of photovoltaic cell V1; V 2 This is provided by energy storage battery V2, which is the output port voltage of energy storage battery V2; here, line losses are ignored, therefore V 1 It is both the output port voltage of photovoltaic cell V1 and the input voltage of the output port. V 2 It is both the output port voltage of the energy storage battery V2 and the input voltage of the output port, so they are the same and will not be distinguished further thereafter. d 1 and d 2 These represent duty cycle 1 and duty cycle 2, respectively.

[0047] This application also proposes a control method for a multi-port high-gain converter in a photovoltaic-storage system. Developing a multi-port high-gain converter facilitates stable control of the DC bus voltage and ensures stable system operation. The method includes at least one of the following steps:

[0048] Switches Q1, Q2, and Q4 are in the ON state, while switches Q3, Q5, and diode D1 are in the OFF state. Photovoltaic cell V1 and energy storage battery V2 charge inductors L1 and L2 to store energy. Energy storage battery V2 and capacitor C2 discharge to inductors L3 and L4. Capacitor Co is in the discharge state.

[0049] Switches Q3, Q4, and Q5 are turned off, and diode D1 is turned on. Energy storage battery V2 and inductor L3 charge capacitor C2, and energy storage battery V2, inductor L3, and inductor L4 charge capacitor C3 simultaneously. Photovoltaic cell V1 charges inductor L1, and energy storage battery V2 charges inductor L2.

[0050] or

[0051] Switches Q1, Q2, and diode D1 are off, while switches Q4, Q3, and Q5 are on. At this time, photovoltaic cell V1, inductor L2, and capacitor C3 discharge to the load and output capacitor Co through switch Q5.

[0052] like Figure 6 As shown, based on the dual-input port topology, the topology proposed in this application can be extended through cascading, as follows: Figure 6 As shown. This method not only increases the number of input ports for the output port but also improves the voltage gain, which is another significant advantage of this application. For example... Figure 6 As shown, it can include multiple expansion units, such as Figure 6 The extended unit #1, extended unit #2, ..., extended unit #n are shown.

[0053] This invention proposes a high-gain multi-input port DC / DC converter topology with expansion capabilities. Based on two input ports, it can be modularly expanded to n input ports. Compared with existing technologies, the proposed topology achieves the same voltage gain while using fewer components, saving system size and cost. With the popularization of the new energy power generation industry, multiple input sources exist in power generation scenarios; the solution in the application embodiment can also expand the dual-port input to a multi-port input system, showing good application prospects. Based on a multi-port high-gain converter, it is beneficial to achieve DC bus voltage stability under various complex operating conditions, which is key to achieving synchronous grid connection and active support control functions in future large-scale photovoltaic-storage coupled DC systems. The topology proposed in this application embodiment can provide greater gain with the same number of devices. That is, the proposed topology uses fewer devices to achieve the same voltage gain. Another advantage of this application is that when a higher converter output voltage level is required, the reverse voltage on the switches and diodes does not exceed the upper limit. Furthermore, this topology has good scalability, allowing for expansion of input ports while increasing the system's voltage gain.

[0054] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0055] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0056] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A multi-port high-gain converter for an optical-storage system, characterized in that, include: Photovoltaic cells, energy storage batteries, first inductor, second inductor, third inductor, fourth inductor, first capacitor, second capacitor, third capacitor, output capacitor, first switch, second switch, third switch, fourth switch, fifth switch, diode; The photovoltaic cell, the third switch, the second switch, and the second inductor are connected in series; the first switch and the first capacitor are connected in series and then in parallel with the third switch; one end of the first inductor is connected between the photovoltaic cell and the second inductor, and the other end is connected between the first switch and the first capacitor; The third capacitor, diode, second capacitor, third inductor, and energy storage battery are connected in series and in parallel with the second and third switches connected in series; the positive terminal of the diode is connected to the second capacitor and the negative terminal of the diode is connected to the third capacitor. The fourth switch is connected in parallel with the third inductor and the energy storage battery, which are connected in series; the fourth inductor is connected in parallel with the second capacitor, the third inductor, and the energy storage battery, which are connected in series. The output capacitor is connected in series with the fifth switch, and then in parallel with the diode, the second capacitor, the third inductor, and the energy storage battery that are connected in series. The first, second, and fourth switches are in the ON state, while the third, fifth, and diodes are in the OFF state; the photovoltaic cell and energy storage battery charge the first and second inductors to store energy; and the energy storage battery and second capacitor discharge to the third and fourth inductors; the output capacitor is in the discharge state. When the third, fourth, and fifth switches are turned off, the diode is turned on; the energy storage battery and the third inductor charge the second capacitor, and the energy storage battery, the third inductor, and the fourth inductor charge the third capacitor simultaneously; the photovoltaic cell charges the first inductor; and the energy storage battery charges the second inductor. The first switch, the second switch, and the diode are off, while the fourth switch, the third switch, and the fifth switch are on. At this time, the photovoltaic cell, the second inductor, and the third capacitor discharge to the load and the output capacitor through the fifth switch.

2. The multi-port high-gain converter for an optical storage system according to claim 1, characterized in that, The relationship between the output port voltage and the supply voltage of the photovoltaic cell and the supply voltage of the energy storage battery is expressed by the following formula: in V 0 Indicates the output port voltage. V 1 This indicates the supply voltage of the photovoltaic cell. V 2 This indicates the supply voltage of the energy storage battery, where V 1 Powered by photovoltaic cells, V 2 Powered by energy storage batteries; d 1 Indicates a duty cycle of 1. d 2 This indicates a duty cycle of 2.

Images