Three-port boost inverter topology and application thereof

Abstract

The invention relates to the technical field of circuit systems, in particular to a three-port boost inverter topology and application thereof. A three-port boost inversion topology is provided, the topology realizes working mode switching by controlling a switch tube, the three-port boost inversion topology structure is cascaded with a traditional Boost converter, according to the change of irradiance, the photovoltaic irradiance range is expanded by using the voltage-multiplying characteristic of a capacitor, the boost multiple of the topology is improved, and the photovoltaic power generation efficiency is improved. The requirement on the capacity of the storage battery is reduced; the common discharge of the photovoltaic device and the storage battery is realized by utilizing the clamping characteristics of the three-port structure and the capacitor; and when the photovoltaic and storage battery output is insufficient to operate the system, the three-phase inverter is used for realizing photovoltaic voltage reduction to charge the storage battery. The objective of the invention is to reduce the power loss of the three-port boost inverter circuit.

Description

Technical Field

[0001] The present application relates to the technical field of circuit systems, and in particular to a three-port boost inverter topology and its application. Background Art

[0002] The output power of photovoltaics is greatly affected by environmental factors such as solar irradiance and temperature. Therefore, in order to maintain stable output of photovoltaics to the load, adding energy storage devices to the photovoltaic system to form a three-port structure of input, output and energy storage ends has become one of the current research hotspots.

[0003] Due to the limited output voltage range of photovoltaic modules, in order to enable the inverter to output voltage and AC power that meets the power requirements of the grid or load, a two-stage boost inverter structure of the Boost circuit is currently often used for boosting. It mainly achieves boosting and AC power conversion respectively through the first-stage boost and second-stage inversion, and uses a pulse signal to control the on-off state of the switch tube in the circuit. This circuit has the advantages of relatively simple structure and control.

[0004] However, when a traditional two-stage converter is used in a three-port boost inverter circuit, all input power in the circuit must undergo two-stage conversion. This will significantly increase the power loss of the highly integrated three-port boost inverter circuit, and the voltage and current stress of the switch tube and diode in the three-port boost inverter circuit will also increase, reducing the conversion efficiency of the overall circuit.

[0005] In view of this, the present application proposes a new three-port boost inverter topology, aiming to reduce the power loss of the three-port boost inverter circuit. Summary of the Invention

[0006] The main purpose of this application is to provide a three-port boost inverter topology, aiming to solve the problem of how to reduce the power loss of the three-port boost inverter circuit.

[0007] To achieve the above objectives, the present application provides a three-port boost inverter topology, which includes:

[0008] Dual input sources, including photovoltaic panels V PV and battery V Bat , where the photovoltaic module V PV and battery V Bat According to the size of the photovoltaic output voltage, the switch tubes Sa1~Sa3 are controlled on / off to switch their own supply / discharge mode;

[0009] The three-port boost inverter topology structure includes a three-phase inverter and a boost capacitor C connected in parallel to the input end of the three-phase full-bridge inverter. o ;

[0010] The three-phase inverter includes switches S1 to S6, diodes VD0 to VD3, inductors L and L1, and switch capacitor C1. The collectors of switches S1, S3, and S5 are connected to each other and connected to boost capacitor C1. o The positive electrode of the switch tube S2, the switch tube S4, and the emitter of the switch tube S6 are connected, and the boost capacitor C o of the negative electrode.

[0011] Optionally, the three-port boost inverter topology further includes an anti-reverse diode VD0, a diode VD1, a diode VD2, a capacitor C Bat , inductor L1 and load;

[0012] Among them, the capacitor C Bat Connect in parallel to the battery V Bat The input terminal, capacitor C Bat The positive electrode of the inductor L1 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the switching capacitor C1, the other end of the switching capacitor C1 is connected between the diode VD1 and the inductor L, the other end of the inductor L is connected to the positive electrode of the diode VD2, and the cathode of the diode VD2 is connected to the boost capacitor C o The positive pole of the load is connected, and the a, b, and c phases of the load are connected between S1 and S4, between S3 and S6, and between S5 and S2 respectively.

[0013] Optionally, the switch tube Sa1 and the switch tube Sa2 are connected in series, the collector of the switch tube Sa1 is connected to the cathode of the diode VD0, and the emitter of the switch tube Sa2 is connected to the photovoltaic module V PV The negative electrode;

[0014] The collector of the switch tube Sa3 is connected between the inductor L and the diode VD2, and the emitter is connected to the capacitor C o of the negative electrode.

[0015] In addition, to achieve the above objectives, the present application also provides a control method for a three-port boost inverter topology, the control method comprising the following steps:

[0016] Collect the current output voltage of the photovoltaic module;

[0017] When the current output voltage is greater than the minimum discharge voltage V2 of the battery and less than or equal to the rated maximum output voltage V max When , the three-port boost inverter topology is controlled to switch to mode 1, so that the photovoltaic components supply energy to the three-phase inverter;

[0018] When the current output voltage is greater than the maximum discharge voltage V1 of the battery and less than or equal to the minimum discharge voltage V2 of the battery, the three-port boost inverter topology is controlled to switch to mode 2 so that the photovoltaic module and the battery jointly drive the load;

[0019] When the current output voltage is greater than the rated minimum output voltage V min , and is less than or equal to the maximum discharge voltage V1 of the battery, the three-port boost inverter topology is controlled to switch to mode three to enable the photovoltaic module to charge the battery.

[0020] Optionally, the step of controlling the three-port boost inverter topology to switch to mode 1 specifically includes:

[0021] When a high-level control signal is received, the control switch tube Sa1 and the diode VD3 are turned off, and the control switch tubes Sa2, Sa3 and the diodes VD1, VD2 are turned on, so that the photovoltaic module V PV The outgoing current passes through diodes VD1, VD2, capacitor C1 and switch tube S2, inductor L1 and switch tube S3 in sequence, and flows back to the negative electrode to form a loop. Capacitor C1 and switch tube S2, inductor L1 and switch tube S3 form a parallel structure. The photovoltaic module V PV Charge capacitor C1 and inductor L1;

[0022] When a low-level control signal is received, the switch tube Sa1 and the diodes VD1 and VD3 are controlled to be turned on, and the switch tubes Sa2, Sa3 and VD2 are controlled to be turned off, so that the current passes through the diode VD1, the switch tube Sa1, the capacitor C1, the inductor L1 and the diode VD3, and the capacitor C1 and the inductor L1 are discharged in series.

[0023] Optionally, the step of controlling the three-port boost inverter topology to switch to mode 2 specifically includes:

[0024] When a high-level control signal is received, the control switch tube Sa1 and the diode VD3 are turned off, and the control switch tubes Sa2, Sa3 and the diodes VD1, VD2 are turned on, so that the photovoltaic module V PV The output current passes through diode VD1, charging capacitor C1 and inductor L, and making battery V Bat The output current passes through the inductor L1 and the switch tube Sa3 to charge the inductor L1;

[0025] When receiving a low-level control signal, the control switches Sa1, Sa2, Sa3, diodes VD1, VD1 and VD2 are turned off, and the control diode VD3 is turned on, so that the battery V Bat Discharge in series with inductor L, capacitor C1, and inductor L.

[0026] Optionally, the step of controlling the three-port boost inverter topology to switch to mode three specifically includes:

[0027] When a high-level control signal is received, the control switch tube Sa1 and the diode VD1 are turned on, and the control switch tubes Sa2, Sa3, diodes VD2 and VD3 are turned off, so that the photovoltaic module V PV The output current passes through diode VD2 and inductor L1 to charge the battery;

[0028] When receiving a low-level control signal, the switch tube Sa3, diode VD1 and diode VD2 are turned on, and the switch tubes Sa1, Sa2 and VD3 are turned off, so that the photovoltaic module V PV The output current is discharged through diodes VD1, VD2, inductor L1 and switch tube Sa3.

[0029] In addition, to achieve the above purpose, the present application also provides a method for selecting components in a three-port boost inverter topology, wherein the components include switch tubes Sa1~Sa3, diodes VD0~VD3, photovoltaic components V PV 、Battery V Bat , switched capacitor C1, inductor L and inductor L1;

[0030] Among them, the voltage stress V of the switch tubes Sa1~Sa3 is Sa1_MAX ~V Sa3_MAX And the voltage stress V of diodes VD1~VD3 VD1_MAX ~V VD3_MAX Satisfy respectively:

[0031]

[0032] Where V PV is the photovoltaic output voltage, V Bat is the battery output voltage, D1 is the duty cycle of mode 1;

[0033] Among them, the current stress I of the switch tubes Sa1~Sa3 Sa1_MAX ~I Sa3_MAX and the current stress I of diodes VD1~VD3 VD1_MAX ~I VD3_MAX Satisfy respectively:

[0034]

[0035] Where, I o is the topology output current, I Bat is the battery output current; D2 and D3 are the duty cycles of mode 2 and mode 3;

[0036] Among them, photovoltaic modules V PV With battery V Bat The voltage stabilizing capacitor C PV 、C Bat , respectively satisfying:

[0037]

[0038] Where, I PV with I Bat are the input currents of photovoltaic and battery respectively; f sw is the switching frequency; D1 and D2 are the duty cycles of the boost converters through which the photovoltaic and battery pass, ∆V PV is the ripple current of the photovoltaic module, ∆V Bat is the ripple voltage of the battery, and satisfies:

[0039]

[0040] Where V in is the input voltage, V out is the output voltage;

[0041] Among them, the capacitance value C1 of the switching capacitor C1 satisfies:

[0042]

[0043] Where, I load is the load current;

[0044] Among them, the inductance value L of the inductor L and the inductance value L1 of the inductor L1 respectively satisfy:

[0045]

[0046] Where, ∆I PV is the ripple current of the photovoltaic module, ∆I Bat is the ripple current of the battery, satisfying:

[0047] .

[0048] In addition, to achieve the above-mentioned purpose, the present application also provides a component selection result obtained by using the component selection method described above.

[0049] This application has at least the following beneficial effects:

[0050] By proposing a three-port boost inverter topology, controlling the switch tube to achieve working mode switching, and cascading the three-port boost inverter topology with the traditional Boost converter, the irradiance range of the photovoltaic power plant is expanded according to the change of irradiance by utilizing the voltage doubling characteristics of the capacitor, thereby improving the boost multiple of the topology and reducing the capacity requirement of the battery. The three-port structure and the clamping characteristics of the capacitor are used to achieve the joint discharge of the photovoltaic power plant and the battery. When the output of the photovoltaic power plant and the battery is insufficient to operate the system, the three-phase inverter is used to reduce the photovoltaic voltage to charge the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a schematic diagram of the structure of a three-port boost inverter topology involved in an embodiment of the present application;

[0052] Figure 2 Schematic diagram of a flow chart of a control method for a three-port boost inverter topology according to an embodiment of the present application;

[0053] Figure 3 Schematic diagram of the charge and discharge equivalent circuit of the topological structure involved in the embodiment of the present application in the first stage and the first state of the modal;

[0054] Figure 4 Schematic diagram of the charge and discharge equivalent circuit of the topological structure involved in the embodiment of the present application in the second state of the first stage of the modal;

[0055] Figure 5 Schematic diagram of the charge and discharge equivalent circuit of the topological structure involved in the embodiment of the present application in the first state of the second mode;

[0056] Figure 6 Schematic diagram of the charge and discharge equivalent circuit of the topological structure involved in the embodiment of the present application in the second state of the second modal stage;

[0057] Figure 7 Schematic diagram of the charge and discharge equivalent circuit of the topological structure involved in the embodiment of the present application in the modal three-stage one state;

[0058] Figure 8 Schematic diagram of the charge and discharge equivalent circuit of the topological structure involved in the embodiment of the present application in the second state of the third modal stage;

[0059] Figure 9 Schematic diagram of the inverter input voltage waveform involved in the embodiment of the present application;

[0060] Figure 10 This is a schematic diagram of the waveform change of the motor speed being constant at the rated speed involved in the embodiment of the present application;

[0061] Figure 11 This is a schematic diagram of the ratio of photovoltaic and battery output power involved in the embodiment of the present application;

[0062] Figure 12 A schematic diagram of the motor speed involved in the embodiment of the present application;

[0063] Figure 13 Schematic diagram of the output characteristics of the system involved in the embodiment of the present application in mode three.

[0064] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0065] To better understand the above technical solutions, exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0066] First embodiment

[0067] The photovoltaic output characteristics are unstable due to environmental influences, so the boost inverter structure is an important part to ensure the stability of the system. The boost capability of the traditional boost circuit is limited and does not have the function of switching the working mode. The boost switch capacitor has significant effects in improving the topology boost capability and reducing the stress of the switch tube. However, the common disadvantage of the three-port and switched capacitor structures is that multiple switching devices are required, which increases the cost and volume while also increasing the loss of the topology and making the control logic of the topology more complicated. Therefore, this embodiment proposes a three-port boost inverter topology, referring to Figure 1 The schematic diagram of the structure of the three-port boost inverter topology is shown, and the three-port boost inverter topology includes:

[0068] Dual input sources, including photovoltaic panels V PV and battery V Bat , where the photovoltaic module V PV and battery V Bat According to the size of the photovoltaic output voltage, the switch tubes Sa1~Sa3 are controlled on / off to switch their own supply / discharge mode;

[0069] The three-port boost inverter topology structure includes a three-phase inverter and a boost capacitor C connected in parallel to the input end of the three-phase full-bridge inverter. o ;

[0070] The three-phase inverter includes switches S1 to S6, diodes VD0 to VD3, inductors L and L1, and switch capacitor C1. The collectors of switches S1, S3, and S5 are connected to each other and connected to boost capacitor C1. o The positive electrode of the switch tube S2, the switch tube S4, and the emitter of the switch tube S6 are connected, and the boost capacitor C o of the negative electrode.

[0071] In this embodiment, the capacitor C1 is controlled by the switch tubes S1 to S6 to connect to the photovoltaic module V PV Parallel charging or series discharging can achieve voltage doubling and boosting. The two currents are respectively generated by the photovoltaic module V PV 、Battery V Bat After flowing out of the positive electrode, it passes through multiple switching tubes and the load and returns to the negative electrode of the power supply to form a loop.

[0072] Traditional boost circuits have limited boost multiples; the input voltage must be greater than the minimum voltage to ensure the output voltage reaches the rated load voltage. By controlling the on / off state of switches S1-S6, the series and parallel connection of the capacitor and PV module is controlled. When the PV module and capacitor are connected in parallel, the PV module charges the capacitor and subsequent inductor. When the PV module and capacitor are connected in series, both discharge together, increasing the input voltage of the boost circuit.

[0073] According to the on-off state of the switch tube, the circuit operation can be divided into multiple different modes to switch its own supply / discharge mode.

[0074] Furthermore, in some optional embodiments, the three-port boost inverter topology further includes an anti-reverse diode VD0, a diode VD1, a diode VD2, a capacitor C Bat , inductor L1 and load;

[0075] Among them, the capacitor C Bat Connect in parallel to the battery V Bat The input terminal, capacitor C Bat The positive electrode of the inductor L1 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the switching capacitor C1, the other end of the switching capacitor C1 is connected between the diode VD1 and the inductor L, the other end of the inductor L is connected to the positive electrode of the diode VD2, and the cathode of the diode VD2 is connected to the boost capacitor C o The positive pole of the load is connected, and the a, b, and c phases of the load are connected between S1 and S4, between S3 and S6, and between S5 and S2 respectively.

[0076] Furthermore, in some optional embodiments, the switch tube Sa1 and the switch tube Sa2 are connected in series, the collector of the switch tube Sa1 is connected to the cathode of the diode VD0, and the emitter of the switch tube Sa2 is connected to the photovoltaic module V PV The collector of the switch tube Sa3 is connected between the inductor L and the diode VD2, and the emitter is connected to the capacitor C o of the negative electrode.

[0077] The technical solution provided in this embodiment proposes a three-port boost inverter topology that controls the switching tube to achieve operating mode switching. The three-port boost inverter topology is cascaded with a traditional Boost converter. Based on changes in irradiance, the voltage-doubling characteristics of capacitors are utilized to expand the irradiance range of the photovoltaic system, increase the topology's voltage boost factor, and reduce battery capacity requirements. The three-port structure and the clamping characteristics of capacitors are used to achieve co-discharge of the photovoltaic system and the battery. When the photovoltaic and battery outputs are insufficient to operate the system, a three-phase inverter is used to step down the photovoltaic voltage to charge the battery.

[0078] Second embodiment

[0079] Based on the first embodiment, in this embodiment, the two current paths of the circuit are generated by two photovoltaic V PV 、Battery V Bat After flowing out of the positive electrode, it passes through multiple switches / diodes and loads and then returns to the negative electrode of the power supply, forming two circuits. The change in solar irradiance causes the change in the output power of the photovoltaic module. The voltage and current output by the photovoltaic module are detected, combined with the output voltage of the battery, and the output voltage V is calculated according to the photovoltaic output voltage. o , the maximum and minimum output voltages are V max 、V min , the maximum charging voltage and minimum discharging voltage of the battery are V1 and V2 respectively, and the topology is divided into three working modes: Figure 2 , the control method of the three-port boost inverter topology includes the following steps:

[0080] Step S10, collecting the current output voltage of the photovoltaic module;

[0081] Step S20: When the current output voltage is greater than the minimum discharge voltage V2 of the battery and less than or equal to the rated maximum output voltage V max When , the three-port boost inverter topology is controlled to switch to mode 1, so that the photovoltaic components supply energy to the three-phase inverter;

[0082] In this step, when the current output voltage is greater than the battery's minimum discharge voltage V, the photovoltaic power supply is independently powered after being boosted by a switched capacitor. Mode 1 is when the photovoltaic power supply is powered by a switched capacitor boost converter. Mode 1 consists of two stages, controlled by a fixed duty cycle signal output to the controller. When the control signal is high, the switch tube remains in the on state, which is stage 1; when the control signal is low, the switch tube remains in the off state, allowing the capacitor and inductor to discharge, which is stage 2. The switching between the two stages is achieved by setting a fixed duty cycle for the signal generator, completing the switching between charging and discharging of the capacitor and inductor, and the circuit switches automatically. The same applies to Modes 2 and 3.

[0083] It should be noted that for the generation of high / low level signals, by setting a working cycle T and the proportion D of the conduction time in the cycle, the switch tube completes one on and one off working state switching within the cycle, and the high level and low level are automatically sent by the signal generator according to the set working cycle T and proportion D. Stage one, stage two and stage three are equivalent.

[0084] In some optional embodiments, referring to Figure 3 The topology shown in the figure is a charge and discharge equivalent circuit in the first stage and the first state of the mode. When a high-level control signal is received, it is the first stage, the control switch Sa1 and the diode VD3 are turned off, and the control switches Sa2, Sa3 and the diodes VD1, VD2 are turned on, so that the photovoltaic module VPV The outgoing current passes through diodes VD1, VD2, capacitor C1 and switch tube S2, inductor L1 and switch tube S3 in sequence, and flows back to the negative electrode to form a loop. Capacitor C1 and switch tube S2, inductor L1 and switch tube S3 form a parallel structure. The photovoltaic module V PV Charge capacitor C1 and inductor L1;

[0085] Reference Figure 4 The charge and discharge equivalent circuit of the topology structure shown in mode one stage two is in stage two when a low-level control signal is received. The switch tube Sa1 and the diodes VD1 and VD3 are controlled to be turned on, and the switch tubes Sa2, Sa3 and VD2 are controlled to be turned off, so that the current passes through the diode VD1, the switch tube Sa1, the capacitor C1, the inductor L1 and the diode VD3, and the capacitor C1 and the inductor L1 are discharged in series.

[0086] Step S30: When the current output voltage is greater than the maximum discharge voltage V1 of the battery and less than or equal to the minimum discharge voltage V2 of the battery, the three-port boost inverter topology is controlled to switch to mode 2 so that the photovoltaic module and the battery jointly drive the load;

[0087] In this step, mode 2 is that the photovoltaic and battery jointly drive the load through the Boost circuit.

[0088] Reference Figure 5 The topology shown in the figure is in the charge and discharge equivalent circuit of the mode 2 stage 1 state. When a high-level control signal is received, it is stage 1, and the control switch tube Sa1 and the diode VD3 are turned off, and the control switches Sa2, Sa3 and the diodes VD1, VD2 are turned on, so that the photovoltaic module V PV The output current passes through diode VD1, charging capacitor C1 and inductor L, and making battery V Bat The output current passes through the inductor L1 and the switch tube Sa3 to charge the inductor L1;

[0089] Reference Figure 6 The topology shown in the figure is in the charge and discharge equivalent circuit of the second stage of the second mode. When the low level control signal is received, it is the second stage. The control switches Sa1, Sa2, Sa3, diodes VD1, VD1 and VD2 are turned off, and the control diode VD3 is turned on to make the battery V Bat Discharge in series with inductor L, capacitor C1, and inductor L.

[0090] Step S40: When the current output voltage is greater than the rated minimum output voltage V min , and is less than or equal to the maximum discharge voltage V1 of the battery, the three-port boost inverter topology is controlled to switch to mode three to enable the photovoltaic module to charge the battery.

[0091] In this step, mode three is photovoltaic charging of the battery.

[0092] Reference Figure 7 The topology shown in the figure is in the charge and discharge equivalent circuit of the modal three-stage one state. When a high-level control signal is received, it is stage one, and the control switch tube Sa1 and the diode VD1 are turned on, and the control switches Sa2, Sa3, diodes VD2 and VD3 are turned off, so that the photovoltaic module V PV The output current passes through diode VD2 and inductor L1 to charge the battery;

[0093] Reference Figure 8 The topology shown in the figure is in the charge and discharge equivalent circuit of the modal three stage two state. When a low-level control signal is received, it is stage two, the switch tube Sa3, the diode VD1 and the diode VD2 are turned on, and the switch tubes Sa1, Sa2 and VD3 are turned off, so that the photovoltaic module V PV The output current is discharged through diodes VD1, VD2, inductor L1 and switch tube Sa3.

[0094] Third embodiment

[0095] Based on the first embodiment, this embodiment provides a method for selecting components in a three-port boost inverter topology, the components involved include switch tubes Sa1~Sa3, diodes VD0~VD3, photovoltaic components V PV 、Battery V Bat , switched capacitor C1, inductor L and inductor L1;

[0096] Among them, the voltage stress V of the switch tubes Sa1~Sa3 is Sa1_MAX ~V Sa3_MAX And the voltage stress V of diodes VD1~VD3 VD1_MAX ~V VD3_MAX Satisfy respectively:

[0097]

[0098] Where V PV is the photovoltaic output voltage, V Bat is the battery output voltage, D1 is the duty cycle of mode 1;

[0099] Among them, the current stress I of the switch tubes Sa1~Sa3 Sa1_MAX ~I Sa3_MAX and the current stress I of diodes VD1~VD3 VD1_MAX ~I VD3_MAX Satisfy respectively:

[0100]

[0101] Where, Io is the topology output current, I Bat is the battery output current; D2 and D3 are the duty cycles of mode 2 and mode 3;

[0102] Among them, photovoltaic modules V PV With battery V Bat The voltage stabilizing capacitor C PV 、C Bat , respectively satisfying:

[0103]

[0104] Where, I PV with I Bat are the input currents of photovoltaic and battery respectively; f sw is the switching frequency; D1 and D2 are the duty cycles of the boost converters through which the photovoltaic and battery pass, ∆V PV is the ripple current of the photovoltaic module, ∆V Bat is the ripple voltage of the battery, and satisfies:

[0105]

[0106] Where V in is the input voltage, V out is the output voltage;

[0107] Among them, the capacitance value C1 of the switching capacitor C1 satisfies:

[0108]

[0109] Where, I load is the load current;

[0110] Among them, the inductance value L of the inductor L and the inductance value L1 of the inductor L1 respectively satisfy:

[0111]

[0112] Where, ∆I PV is the ripple current of the photovoltaic module, ∆I Bat is the ripple current of the battery, satisfying:

[0113] .

[0114] Fourth embodiment

[0115] Based on the third embodiment, this embodiment provides a component selection result obtained by using the component selection method described in the third embodiment.

[0116] In some specific implementations, the selection results are shown in Table 1, Table 2 and Table 3:

[0117] Table 1. Device parameter selection results

[0118]

[0119] Table 2. Photovoltaic and battery parameters

[0120]

[0121] In addition, this embodiment provides an application of a three-port boost inverter topology in a photovoltaic water pumping system. A motor pump is a key component in this system. The output power from the photovoltaic and battery is boosted and inverted to drive the motor, which then pulls the pump via its rotating shaft to pump water. The motor and pump operate through physical transmission. To explore the relationship between motor speed and inverter input voltage, this design uses a three-phase asynchronous motor as the load. Its parameters are shown in Table 3. Field-Oriented Control (FOC) is used to achieve precise motor control.

[0122] Table 3. Motor parameters

[0123]

[0124] Fifth embodiment

[0125] Based on any of the foregoing embodiments, in this embodiment, Figures 9-10 The output characteristic of the system in mode 1. In order to maintain the long-term operation of the motor, it is necessary to ensure that the motor speed is the rated speed. Therefore, whether each mode can maintain the motor running at the rated speed is used as the dividing standard. When the irradiance is 750W / m 2 When the motor speed is rated speed, the irradiance is 750~1000 W / m 2 In the simulation, the irradiance changes from 1000 to 750 W / m in 3 s. 2 The photovoltaic output power decreases from 1890 W to 1150 W due to the step change. The duty cycle of the switched capacitor type boost conversion is 0.5, which boosts the photovoltaic voltage and inputs it into the inverter. The output voltage of the switched capacitor structure is twice the input voltage, achieving voltage doubling. Therefore, the inverter input voltage waveform at this time is as follows: Figure 9 As shown in the figure, V PV is the photovoltaic input voltage, V Bat is the battery input voltage, V dc is the DC side output voltage (i.e. the inverter topology input voltage).

[0126] The motor speed is constant at the rated speed, and the waveform changes as follows Figure 10 shown.

[0127] Figures 11-12 is the output characteristic of the system in mode 2. The solar irradiance is between 500 and 750 W / m 2 When the power is 100W, the motor is driven by photovoltaic and battery together. The output power of photovoltaic and battery accounts for Figure 11 As shown in the figure, P PV is the photovoltaic output power, P Bat is the battery output power, P 总 The total power output of photovoltaic and battery. The irradiance is 500 to 750 W / m in 3 s. 2 The step change of PV output power in the total power increases from 0.65 to 0.97. Figure 12 As shown, when the irradiance is 500 W / m 2 , the output power ratio of photovoltaic and battery is 0.5, 0.5, which makes it impossible for the motor to run at rated speed.

[0128] Figure 13 is the output characteristic of the system in mode three. In the figure, P PV is the photovoltaic output power, P Bat is the battery output power, and the efficiency is the photovoltaic power through the switch tube S a1 With S a2 The solar irradiance is between 185 and 500 W / m 2 When the irradiance is lower than 185 W / m, the output of photovoltaic and battery is insufficient to drive the motor, so the power output of photovoltaic is used to charge the battery. The maximum charging efficiency is 99.73%. 2 When the PV output is insufficient to charge the battery.

[0129] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0130] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A three-port boost inverter topology, characterized in that: The three-port boost inverter topology includes: Dual input sources, including photovoltaic panels V PV and battery V Bat , where the photovoltaic module V PV and battery V Bat According to the size of the photovoltaic output voltage, the switch tubes Sa1~Sa3 are controlled on / off to switch their own supply / discharge mode; The three-port boost inverter topology structure includes a three-phase inverter and a boost capacitor C connected in parallel to the input end of the three-phase full-bridge inverter. o ; The three-phase inverter includes switches S1 to S6, diodes VD0 to VD3, inductors L and L1, and switch capacitor C1. The collectors of switches S1, S3, and S5 are connected to each other and connected to boost capacitor C1. o The positive electrode of the switch tube S2, the switch tube S4, and the emitter of the switch tube S6 are connected, and the boost capacitor C o of the negative electrode.

2. The three-port boost inverter topology according to claim 1, wherein: The three-port boost inverter topology also includes an anti-reverse diode VD0, a diode VD1, a diode VD2, a capacitor C Bat , inductor L1 and load; Among them, the capacitor C Bat Connect in parallel to the battery V Bat The input terminal, capacitor C Bat The positive electrode of the inductor L1 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the switching capacitor C1, the other end of the switching capacitor C1 is connected between the diode VD1 and the inductor L, the other end of the inductor L is connected to the positive electrode of the diode VD2, and the cathode of the diode VD2 is connected to the boost capacitor C o The positive pole of the load is connected, and the a, b, and c phases of the load are connected between S1 and S4, between S3 and S6, and between S5 and S2 respectively.

3. The three-port boost inverter topology according to claim 1, wherein: The switch tube Sa1 and the switch tube Sa2 are connected in series, the collector of the switch tube Sa1 is connected to the cathode of the diode VD0, and the emitter of the switch tube Sa2 is connected to the photovoltaic module V PV The negative electrode; The collector of the switch tube Sa3 is connected between the inductor L and the diode VD2, and the emitter is connected to the capacitor C o of the negative electrode.

4. A control method applied to a three-port boost inverter topology according to any one of claims 1 to 3, characterized in that: The control method comprises the following steps: Collect the current output voltage of the photovoltaic module; When the current output voltage is greater than the minimum discharge voltage V2 of the battery and less than or equal to the rated maximum output voltage V max When , the three-port boost inverter topology is controlled to switch to mode 1, so that the photovoltaic components supply energy to the three-phase inverter; When the current output voltage is greater than the maximum discharge voltage V1 of the battery and less than or equal to the minimum discharge voltage V2 of the battery, the three-port boost inverter topology is controlled to switch to mode 2 so that the photovoltaic module and the battery jointly drive the load; When the current output voltage is greater than the rated minimum output voltage V min , and is less than or equal to the maximum discharge voltage V1 of the battery, the three-port boost inverter topology is controlled to switch to mode three to enable the photovoltaic module to charge the battery.

5. The control method of the three-port boost inverter topology according to claim 4, characterized in that: The step of controlling the three-port boost inverter topology to switch to mode 1 specifically includes: When a high-level control signal is received, the control switch tube Sa1 and the diode VD3 are turned off, and the control switch tubes Sa2, Sa3 and the diodes VD1, VD2 are turned on, so that the photovoltaic module V PV The outgoing current passes through diodes VD1, VD2, capacitor C1 and switch tube S2, inductor L1 and switch tube S3 in sequence, and flows back to the negative electrode to form a loop. Capacitor C1 and switch tube S2, inductor L1 and switch tube S3 form a parallel structure. The photovoltaic module V PV Charge capacitor C1 and inductor L1; When a low-level control signal is received, the switch tube Sa1 and the diodes VD1 and VD3 are controlled to be turned on, and the switch tubes Sa2, Sa3 and VD2 are controlled to be turned off, so that the current passes through the diode VD1, the switch tube Sa1, the capacitor C1, the inductor L1 and the diode VD3, and the capacitor C1 and the inductor L1 are discharged in series.

6. The control method of the three-port boost inverter topology according to claim 4, characterized in that: The step of controlling the three-port boost inverter topology to switch to mode 2 specifically includes: When a high-level control signal is received, the control switch tube Sa1 and the diode VD3 are turned off, and the control switch tubes Sa2, Sa3 and the diodes VD1, VD2 are turned on, so that the photovoltaic module V PV The output current passes through diode VD1, charging capacitor C1 and inductor L, and making battery V Bat The output current passes through the inductor L1 and the switch tube Sa3 to charge the inductor L1; When receiving a low-level control signal, the control switches Sa1, Sa2, Sa3, diodes VD1, VD1 and VD2 are turned off, and the control diode VD3 is turned on, so that the battery V Bat Discharge in series with inductor L, capacitor C1, and inductor L.

7. The control method of the three-port boost inverter topology according to claim 4, characterized in that: The steps of controlling the three-port boost inverter topology to switch to mode three include: When a high-level control signal is received, the control switch tube Sa1 and the diode VD1 are turned on, and the control switch tubes Sa2, Sa3, diodes VD2 and VD3 are turned off, so that the photovoltaic module V PV The output current passes through diode VD2 and inductor L1 to charge the battery; When receiving a low-level control signal, the switch tube Sa3, diode VD1 and diode VD2 are turned on, and the switch tubes Sa1, Sa2 and VD3 are turned off, so that the photovoltaic module V PV The output current is discharged through diodes VD1, VD2, inductor L1 and switch tube Sa3.

8. A method for selecting components used in a three-port boost inverter topology according to any one of claims 1 to 3, characterized in that: The components include switch tubes Sa1~Sa3, diodes VD0~VD3, photovoltaic components V PV 、Battery V Bat , switched capacitor C1, inductor L and inductor L1; Among them, the voltage stress V of the switch tubes Sa1~Sa3 is Sa1_MAX ~V Sa3_MAX And the voltage stress V of diodes VD1~VD3 VD1_MAX ~V VD3_MAX Satisfy respectively: ； Where V PV is the photovoltaic output voltage, V Bat is the battery output voltage, D1 is the duty cycle of mode 1; Among them, the current stress I of the switch tubes Sa1~Sa3 Sa1_MAX ~I Sa3_MAX and the current stress I of diodes VD1~VD3 VD1_MAX ~I VD3_MAX Satisfy respectively: ； Where, I o is the topology output current, I Bat is the battery output current; D2 and D3 are the duty cycles of mode 2 and mode 3; Among them, photovoltaic modules V PV With battery V Bat The voltage stabilizing capacitor C PV 、C Bat , respectively satisfying: ； Where, I PV with I Bat are the input currents of photovoltaic and battery respectively; f sw is the switching frequency; D1 and D2 are the duty cycles of the boost converters through which the photovoltaic and battery pass, ∆V PV is the ripple current of the photovoltaic module, ∆V Bat is the ripple voltage of the battery, and satisfies: ； Where V in is the input voltage, V out is the output voltage; Among them, the capacitance value C1 of the switching capacitor C1 satisfies: ； Where, I load is the load current; Among them, the inductance value L of the inductor L and the inductance value L1 of the inductor L1 respectively satisfy: ； Where, ∆I PV is the ripple current of the photovoltaic module, ∆I Bat is the battery ripple current, satisfying: 。 9. A component selection result obtained by using the component selection method in a three-port boost inverter topology according to claim 8.

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