Three-port boost inverter topology and its applications

Abstract

This application relates to the field of circuit system technology, and in particular to a three-port boost inverter topology and its application. By proposing a three-port boost inverter topology, which achieves operating mode switching through controlled switching transistors, the topology is cascaded with a traditional Boost converter. Based on changes in irradiance, the voltage multiplication characteristic of the capacitor is utilized to expand the irradiance range of the photovoltaic system, thereby increasing the boost ratio and reducing the capacity requirements of the battery. The three-port structure and the clamping characteristics of the capacitor enable simultaneous discharge of the photovoltaic system and the battery. When the output from the photovoltaic system and the battery is insufficient to operate the system, a three-phase inverter is used to step down the photovoltaic voltage to charge the battery. The aim is to reduce the power loss of the three-port boost inverter circuit.

Description

Technical Field

[0001] This application relates to the field of circuit system technology, and in particular to a three-port boost inverter topology and its application. Background Technology

[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 and forming a three-port boost inverter circuit with input, output and energy storage has become one of the current research hotspots.

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

[0004] However, when a traditional two-stage converter is applied to a three-port boost inverter circuit, all the input power in the circuit must undergo two stages of conversion. For a highly integrated three-port boost inverter circuit, this will significantly increase its power loss. Furthermore, the voltage and current stress on the switching transistors and diodes in the three-port boost inverter circuit will also increase, reducing the overall conversion efficiency of the circuit.

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

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

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

[0008] Dual input sources, including photovoltaic modules V PV and storage battery V Bat Among them, photovoltaic module V PV and storage battery V Bat The switching transistors Sa1, Sa2, and Sa3 are controlled to switch on / off according to the magnitude of the photovoltaic output voltage, so as to switch their own power supply / discharge mode.

[0009] A three-port boost inverter topology includes a three-phase inverter and a boost capacitor C connected in parallel at the input of the three-phase full-bridge inverter. oIt also includes reverse polarity protection diode VD0, diode VD1, diode VD2, and capacitor C. Bat , switched capacitor C1, inductor L1, inductor L, load, switching transistor Sa1, switching transistor Sa2 and switching transistor Sa3;

[0010] The three-phase inverter includes switching transistors S1, S2, S3, S4, S5, and S6. The collectors of switching transistors S1, S3, and S5 are connected together and connected to a boost capacitor C. o The positive terminal of the transistor is connected to the emitter of switching transistors S2, S4, and S6, and then connected to the boost capacitor C. o The negative electrode.

[0011] The anode of the diode VD0 is connected to the photovoltaic module V. PV The positive terminal; capacitor C Bat The positive terminal of the battery is connected to V. Bat The positive terminal and one end of the inductor L1, capacitor C Bat The negative terminal of the battery is connected to V. Bat The negative terminal of the diode is connected to the inductor; the other end of the inductor L1 is connected to one end of the switched capacitor C1, the other end of the switched capacitor C1 is connected to the cathode of the diode VD1 and one end of the inductor L, the other end of the inductor L is connected to the anode of the diode VD2, and the cathode of the diode VD2 is connected to the boost capacitor C. o The positive terminals are connected, and the three phases a, b, and c of the load are connected between switch S1 and switch S4, between switch S3 and switch S6, and between switch S5 and switch S2, respectively.

[0012] Optionally, switching transistors Sa1 and Sa2 are connected in series. The collector of switching transistor Sa1 is connected to the cathode of diode VD0 and the anode of diode VD1, and the emitter of switching transistor Sa2 is connected to the photovoltaic module VD1. PV The negative electrode;

[0013] The collector of the switching transistor Sa3 is connected between the inductor L and the diode VD2, and the emitter is connected to the capacitor C. o negative electrode, photovoltaic module V PV The negative electrode and the battery V Bat The negative electrode.

[0014] Furthermore, to achieve the above objectives, this application also provides a control method for a three-port boost inverter topology, the control method comprising the following steps:

[0015] Collect the current output voltage of the photovoltaic module;

[0016] 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 of the photovoltaic module... maxAt that time, the control three-port boost inverter topology is switched to mode one so that the photovoltaic modules can supply energy to the three-phase inverter;

[0017] 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 switched to mode two so that the photovoltaic module and the battery can drive the load together.

[0018] When the current output voltage is greater than the rated minimum output voltage V of the photovoltaic module min When the voltage is less than or equal to the maximum discharge voltage V1 of the battery, the three-port boost inverter topology is switched to mode three so that the photovoltaic modules can charge the battery.

[0019] Optionally, the step of controlling the three-port boost inverter topology to switch to mode one specifically includes:

[0020] Upon receiving a high-level control signal, control switch Sa1 and diode VD2 are turned off, while control switches Sa2 and Sa3, along with diodes VD0 and VD1, are turned on, thereby enabling the photovoltaic module V... PV The outflowing current sequentially passes through diode VD0, diode VD1, capacitor C1 and switch S2, inductor L1 and switch S3, and flows back to the negative terminal to form a circuit. Capacitor C1 and switch S2, and inductor L1 and switch S3 form a parallel structure. The photovoltaic module V... PV Charge capacitor C1 and inductor L1;

[0021] When a low-level control signal is received, the control switch Sa1 is turned on with diodes VD0 and VD2, and the control switch Sa2 and Sa3 are turned off with diode VD1, so that current flows through diode VD0, switch Sa1, capacitor C1, inductor L1 and diode VD2, and capacitor C1 and inductor L1 discharge in series.

[0022] Optionally, the step of controlling the three-port boost inverter topology to switch to mode two specifically includes:

[0023] Upon receiving a high-level control signal, control switch Sa1 and diode VD2 are turned off, while control switches Sa2 and Sa3, along with diodes VD0 and VD1, are turned on, thereby enabling the photovoltaic module V... PV The output current passes through diode VD0, charging capacitor C1 and inductor L, and also powering battery V. Bat The output current passes through inductor L1 and switching transistor Sa3, charging inductor L1.

[0024] Upon receiving a low-level control signal, control switches Sa1, Sa2, and Sa3, diode VD0, and diode VD1 are turned off, while control diode VD2 is turned on, so that the battery V... Bat Discharge in series with inductor L, capacitor C1, and inductor L.

[0025] Optionally, the steps for controlling the three-port boost inverter topology to switch to mode three specifically include:

[0026] Upon receiving a high-level control signal, control switch Sa1 and diode VD0 are turned on, while control switches Sa2 and Sa3, diodes VD1 and VD2 are turned off, thereby turning off the photovoltaic module V. PV The output current charges the battery through diode VD1 and inductor L1.

[0027] Upon receiving a low-level control signal, switch Sa3, diodes VD0 and VD1 are turned on, while switch Sa1, switch Sa2, and diode VD2 are turned off, thereby enabling the photovoltaic module V... PV The output current discharges through diode VD0, diode VD1, inductor L1 and switching transistor Sa3.

[0028] Furthermore, to achieve the above objectives, this application also provides a method for selecting components in a three-port boost inverter topology, wherein the components include switching transistors Sa1, Sa2, and Sa3, diodes VD0, VD1, and VD2, and a photovoltaic module V. PV Storage battery V Bat Switched capacitor C1, inductor L and inductor L1;

[0029] Among them, switching transistors Sa1, Sa2, and Sa3 correspond to voltage stress V, respectively. Sa1_MAX Voltage stress V Sa2_MAX and voltage stress V Sa3_MAX And the voltage stress V corresponding to diodes VD0, VD1, and VD2 respectively. VD0_MAX Voltage stress V VD1_MAX and voltage stress V VD2_MAX They respectively satisfy:

[0030]

[0031] In the formula, V PV V is the output voltage of the photovoltaic system. Bat D1 represents the battery output voltage, and D1 represents the mode-duty cycle.

[0032] Among them, switching transistors Sa1, Sa2, and Sa3 correspond to current stress I, respectively. Sa1_MAX Current stress ISa2_MAX and current stress I Sa3_MAX And the current stress I corresponding to diodes VD0, VD1, and VD2 respectively. VD0_MAX Current stress I VD1_MAX Current stress I VD2_MAX They respectively satisfy:

[0033]

[0034] In the formula, I o For the topology output current, I Bat D1 represents the battery output current; D2 and D3 represent the duty cycles of mode two and mode three, respectively.

[0035] Among them, photovoltaic module V PV With storage battery V Bat Zener capacitor C PV C Bat They respectively satisfy:

[0036]

[0037] In the formula, I PV with I Bat These are the input currents of the photovoltaic system and the battery, respectively; f sw D1 and D2 are the switching frequency; D1 and D2 are the duty cycles of the boost converter through which the photovoltaic cells and batteries pass, ∆V. PV The ripple current of the photovoltaic module is ∆V. Bat Let be the ripple voltage of the battery, and satisfy:

[0038]

[0039] In the formula, V in V is the input voltage. out This refers to the output voltage.

[0040] The capacitance value C1 of the switched capacitor C1 satisfies:

[0041]

[0042] In the formula, I load This is the load current;

[0043] Wherein, the inductance value L of inductor L and the inductance value L1 of inductor L1 satisfy the following conditions respectively:

[0044]

[0045] In the formula, ∆I PV The ripple current of the photovoltaic module is ∆I. Bat For the ripple current of the battery, satisfy:

[0046] .

[0047] In addition, to achieve the above objectives, this application also provides a component selection result obtained by using the component selection method described above.

[0048] This application has at least the following beneficial effects:

[0049] By proposing a three-port boost inverter topology, the operating mode switching is achieved by controlling the switching transistors. The three-port boost inverter topology is cascaded with a traditional Boost converter. According to the change of irradiance, the voltage multiplication characteristic of the capacitor is used to expand the irradiance range of the photovoltaic system, thereby increasing the boost factor of the topology and reducing the capacity requirements of the battery. The three-port structure and the clamping characteristic of the capacitor are used to enable the photovoltaic system and the battery to discharge together. When the output of the photovoltaic system and the battery is insufficient to operate the system, the three-phase inverter is used to step down the photovoltaic voltage to charge the battery. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the three-port boost inverter topology involved in the embodiments of this application;

[0051] Figure 2 This is a flowchart illustrating the control method of the three-port boost inverter topology involved in the embodiments of this application;

[0052] Figure 3 This is a schematic diagram of the charging and discharging equivalent circuit of the topology involved in the embodiments of this application in a mode-one-stage-one-state.

[0053] Figure 4 This is a schematic diagram of the charging and discharging equivalent circuit of the topology involved in the embodiments of this application in mode one, stage two states;

[0054] Figure 5 This is a schematic diagram of the charging and discharging equivalent circuit of the topology involved in the embodiments of this application in the mode two-stage one state;

[0055] Figure 6 This is a schematic diagram of the charging and discharging equivalent circuit of the topology involved in the embodiments of this application in the two-mode, two-state mode;

[0056] Figure 7 This is a schematic diagram of the charging and discharging equivalent circuit of the topology involved in the embodiments of this application in the three-stage-one-state mode;

[0057] Figure 8 This is a schematic diagram of the charging and discharging equivalent circuit of the topology involved in the embodiments of this application in the three-stage two-state mode;

[0058] Figure 9 This is a schematic diagram of the inverter input voltage waveform involved in an embodiment of this application;

[0059] Figure 10 This is a schematic diagram of the waveform variation of a motor with a constant rated speed, as described in an embodiment of this application.

[0060] Figure 11 This is a schematic diagram illustrating the output power ratio of photovoltaic and battery in an embodiment of this application;

[0061] Figure 12 This is a schematic diagram of the motor speed involved in the embodiments of this application;

[0062] Figure 13 This is a schematic diagram of the output characteristics of the system involved in the embodiments of this application in mode three.

[0063] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0064] To better understand the above technical solutions, exemplary embodiments of this disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0065] First Embodiment

[0066] Photovoltaic output characteristics are unstable due to environmental influences, making the boost inverter structure a crucial component for ensuring system stability. Traditional boost circuits have limited boost capabilities and lack mode switching functionality. Boost-type switched capacitors have shown significant effectiveness in improving topology boost capability and reducing switching transistor stress. However, a common drawback of both three-port and switched capacitor structures is the need for multiple switching devices, increasing cost and size, topology losses, and making the topology's control logic more complex. Therefore, this embodiment proposes a three-port boost inverter topology, referring to... Figure 1 The diagram shown illustrates the structure of a three-port boost inverter topology, which includes:

[0067] Dual input sources, including photovoltaic modules V PV and storage battery V Bat Among them, photovoltaic module V PV and storage battery V Bat The switching transistors Sa1, Sa2, and Sa3 are controlled to switch on / off according to the magnitude of the photovoltaic output voltage, so as to switch their own power supply / discharge mode.

[0068] A three-port boost inverter topology includes a three-phase inverter and a boost capacitor C connected in parallel at the input of the three-phase full-bridge inverter. o It also includes reverse polarity protection diode VD0, diode VD1, diode VD2, and capacitor C. Bat , switched capacitor C1, inductor L1, inductor L, load, switching transistor Sa1, switching transistor Sa2 and switching transistor Sa3;

[0069] The three-phase inverter includes switching transistors S1, S2, S3, S4, S5, and S6. The collectors of switching transistors S1, S3, and S5 are connected together and connected to a boost capacitor C. o The positive terminal of the transistor is connected to the emitter of switching transistors S2, S4, and S6, and then connected to the boost capacitor C. o The negative electrode.

[0070] In this embodiment, capacitor C1 is controlled by switches S1, S2, S3, S4, S5, and S6 to interact with the photovoltaic module V. PV Parallel charging or series discharging achieves voltage multiplication and boosting; the two currents are respectively supplied by the photovoltaic module V. PV Storage battery V Bat After flowing out from the positive terminal, it passes through multiple switching transistors and the load before returning to the negative terminal of the power supply, forming a circuit.

[0071] Traditional Boost circuits have limited boost ratios; the input voltage must be greater than a minimum voltage to ensure the output voltage is the rated load voltage. By controlling the on / off states of switches S1, S2, S3, S4, S5, and S6, the series and parallel connection of the capacitor and photovoltaic module can be controlled. When the photovoltaic module and capacitor are connected in parallel, the photovoltaic module charges the capacitor and the subsequent inductor; when the photovoltaic module and capacitor are connected in series, they discharge together, increasing the input voltage of the Boost circuit.

[0072] Based on the on / off state of the switching transistor, the circuit operation can be divided into several different modes to switch its own power supply / discharge mode.

[0073] The anode of diode VD0 is connected to the photovoltaic module V. PV The positive electrode;

[0074] Capacitor C Bat The positive terminal of the battery is connected to V. Bat The positive terminal and one end of the inductor L1, capacitor C Bat The negative terminal of the battery is connected to V. BatThe negative terminal of the diode is connected to the inductor; the other end of the inductor L1 is connected to one end of the switched capacitor C1, the other end of the switched capacitor C1 is connected to the cathode of the diode VD1 and one end of the inductor L, the other end of the inductor L is connected to the anode of the diode VD2, and the cathode of the diode VD2 is connected to the boost capacitor C. o The positive terminals are connected, and the three phases a, b, and c of the load are connected between switch S1 and switch S4, between switch S3 and switch S6, and between switch S5 and switch S2, respectively. Further, in some optional embodiments, switch Sa1 and switch Sa2 are connected in series, with the collector of switch Sa1 connected to the cathode of diode VD0 and the anode of diode VD1, and the emitter of switch Sa2 connected to the photovoltaic module V... PV The negative terminal; the collector of the switching transistor Sa3 is connected between the inductor L and the diode VD2, and the emitter is connected to the capacitor C. o negative electrode, photovoltaic module V PV The negative electrode and the battery V Bat The negative electrode.

[0075] This embodiment proposes a three-port boost inverter topology, controlling the switching transistors to achieve operating mode switching. The three-port boost inverter topology is cascaded with a traditional Boost converter. Based on variations in irradiance, the voltage multiplication characteristic of the capacitor expands the irradiance range of the photovoltaic system, increasing the boost ratio of the topology and reducing the capacity requirements of the battery. The three-port structure and the clamping characteristics of the capacitor enable simultaneous discharge of the photovoltaic system and the battery. When the output from the photovoltaic system and the battery is insufficient to operate the system, a three-phase inverter is used to step down the photovoltaic voltage to charge the battery.

[0076] Second Embodiment

[0077] Based on the first embodiment, in this embodiment, the two currents of the circuit are generated by two photovoltaic V PV Storage battery V Bat After flowing out from the positive terminal, the current passes through multiple switches / diodes and the load before returning to the negative terminal of the power supply, forming two circuits. Changes in solar irradiance cause changes in the output power of the photovoltaic module. By detecting the output voltage and current of the photovoltaic module and combining this with the battery's output voltage, the photovoltaic output voltage V is determined. o The maximum and minimum output voltages are respectively V max V min Based on the relationship between the maximum charging voltage and the minimum discharging voltage of the battery, V1 and V2 respectively, this topology is divided into three operating modes: (Refer to...) Figure 2 The control method for a three-port boost inverter topology includes the following steps:

[0078] Step S10: Collect the current output voltage of the photovoltaic module;

[0079] 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 of the photovoltaic module... max At that time, the control three-port boost inverter topology is switched to mode one so that the photovoltaic modules can supply energy to the three-phase inverter;

[0080] In this step, when the current output voltage is greater than the minimum discharge voltage V of the battery, the photovoltaic power supply is independently powered after being boosted by the switched capacitor. Mode 1 involves the photovoltaic power supplying energy to the inverter via a switched capacitor boost converter. Mode 1 includes two stages, controlled by outputting a signal with a fixed duty cycle to the controller. When the control signal is high, the switching transistor remains on (stage 1); when the control signal is low, the switching transistor remains off, allowing the capacitor and inductor to discharge (stage 2). The switching between the two stages is achieved by setting a fixed duty cycle for the signal generator, completing the charging and discharging switching of the capacitor and inductor. This is a self-switching circuit. The subsequent Modes 2 and 3 follow the same principle.

[0081] It should be noted that for the generation of high / low level signals, by setting a working period T and the proportion D of the conduction time within that period, the switching transistor completes one on and one off state switching within that period. The high and low levels are automatically sent by the signal generator according to the set working period T and proportion D. Stage 1, Stage 2 and Stage 3 are the same.

[0082] In some alternative implementations, refer to Figure 3 The charging and discharging equivalent circuit of the topology shown in mode one, phase one state, is in phase one when a high-level control signal is received. This controls the switching transistor Sa1 and diode VD2 to turn off, and controls the switching transistors Sa2 and Sa3 and diodes VD0 and VD1 to turn on, so that the photovoltaic module V... PV The outflowing current sequentially passes through diode VD0, diode VD1, capacitor C1 and switch S2, inductor L1 and switch S3, and flows back to the negative terminal to form a circuit. Capacitor C1 and switch S2, and inductor L1 and switch S3 form a parallel structure. The photovoltaic module V... PV Charge capacitor C1 and inductor L1;

[0083] Reference Figure 4 The charging and discharging equivalent circuit of the topology shown in mode one phase two state is in phase two when a low-level control signal is received. It controls the switching transistor Sa1 to conduct with diodes VD0 and VD2, and controls the switching transistors Sa2 and Sa3 to turn off with diode VD1, so that current flows through diode VD0, switching transistor Sa1, capacitor C1, inductor L1 and diode VD2, and capacitor C1 and inductor L1 discharge in series.

[0084] 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, control the three-port boost inverter topology to switch to mode two so that the photovoltaic module and the battery can drive the load together.

[0085] In this step, mode two involves the photovoltaic system and the battery driving the load together via a Boost circuit.

[0086] Reference Figure 5 The charging and discharging equivalent circuit of the topology shown in mode two, stage one state, is in stage one when a high-level control signal is received. This stage controls switch Sa1 and diode VD2 to turn off, and controls switches Sa2 and Sa3 and diodes VD0 and VD1 to turn on, thereby enabling the photovoltaic module V... PV The output current passes through diode VD0, charging capacitor C1 and inductor L, and also powering battery V. Bat The output current passes through inductor L1 and switching transistor Sa3, charging inductor L1.

[0087] Reference Figure 6 The charging and discharging equivalent circuit of the topology shown in mode two, stage two state, is in stage two when a low-level control signal is received. This stage controls the switching transistors Sa1, Sa2, and Sa3, as well as diodes VD0 and VD1 to turn off, and controls diode VD2 to turn on, so that the battery V... Bat Discharge in series with inductor L, capacitor C1, and inductor L.

[0088] Step S40, when the current output voltage is greater than the rated minimum output voltage V of the photovoltaic module min When the voltage is less than or equal to the maximum discharge voltage V1 of the battery, the three-port boost inverter topology is switched to mode three so that the photovoltaic modules can charge the battery.

[0089] In this step, mode 3 is where the photovoltaic system charges the battery.

[0090] Reference Figure 7 The illustrated topology, in its charge / discharge equivalent circuit under mode three-stage-one state, is in stage one upon receiving a high-level control signal. This stage controls the conduction of switch Sa1 and diode VD0, and the turn-off of switches Sa2 and Sa3, diodes VD1 and VD2, thereby enabling the photovoltaic module V... PV The output current charges the battery through diode VD1 and inductor L1.

[0091] Reference Figure 8The topology shown is in the charging and discharging equivalent circuit of the three-stage two-state mode. When a low-level control signal is received, it is in stage two. Switch Sa3, diode VD0, and diode VD1 are turned on, while switch Sa1, switch Sa2, and diode VD2 are turned off, so that the photovoltaic module V... PV The output current discharges through diodes VD0 and VD1, inductor L1, and switching transistor Sa3.

[0092] Third Embodiment

[0093] Based on the first embodiment, this embodiment provides a method for selecting components in a three-port boost inverter topology. The components involved include switching transistors Sa1, Sa2, and Sa3, diodes VD0, VD1, and VD2, and a photovoltaic module V. PV Storage battery V Bat Switched capacitor C1, inductor L and inductor L1;

[0094] Among them, switching transistors Sa1, Sa2, and Sa3 correspond to voltage stress V, respectively. Sa1_MAX Voltage stress V Sa2_MAX and voltage stress V Sa3_MAX And the voltage stress V corresponding to diodes VD0, VD1, and VD2 respectively. VD0_MAX Voltage stress V VD1_MAX and voltage stress V VD2_MAX They respectively satisfy:

[0095]

[0096] In the formula, V PV V is the output voltage of the photovoltaic system. Bat D1 represents the battery output voltage, and D1 represents the mode-duty cycle.

[0097] Among them, switching transistors Sa1, Sa2, and Sa3 correspond to current stress I, respectively. Sa1_MAX Current stress I Sa2_MAX and current stress I Sa3_MAX And the current stress I corresponding to diodes VD0, VD1, and VD2 respectively. VD0_MAX Current stress I VD1_MAX Current stress I VD2_MAX They respectively satisfy:

[0098]

[0099] In the formula, I o For the topology output current, I Bat D1 represents the battery output current; D2 and D3 represent the duty cycles of mode two and mode three, respectively.

[0100] Among them, photovoltaic module V PV With storage battery V Bat Zener capacitor C PV C Bat They respectively satisfy:

[0101]

[0102] In the formula, I PV with I Bat These are the input currents of the photovoltaic system and the battery, respectively; f sw D1 and D2 are the switching frequency; D1 and D2 are the duty cycles of the boost converter through which the photovoltaic cells and batteries pass, ∆V. PV The ripple current of the photovoltaic module is ∆V. Bat Let be the ripple voltage of the battery, and satisfy:

[0103]

[0104] In the formula, V in V is the input voltage. out This refers to the output voltage.

[0105] The capacitance value C1 of the switched capacitor C1 satisfies:

[0106]

[0107] In the formula, I load This is the load current;

[0108] Wherein, the inductance value L of inductor L and the inductance value L1 of inductor L1 satisfy the following conditions respectively:

[0109]

[0110] In the formula, ∆I PV The ripple current of the photovoltaic module is ∆I. Bat For the ripple current of the battery, satisfy:

[0111] .

[0112] Fourth embodiment

[0113] Based on the third embodiment, this embodiment provides a component selection result obtained by using the component selection method described in the third embodiment.

[0114] In some specific implementations, the selection results are shown in Tables 1, 2, and 3:

[0115] Table 1. Component Parameter Selection Results

[0116]

[0117] Table 2. Photovoltaic and Battery Parameters

[0118]

[0119] In addition, this embodiment provides an application of a three-port boost inverter topology in a photovoltaic water pumping system. The motor-driven water pump is an important device in the photovoltaic water pumping system. The output power of the photovoltaic system and the battery is boosted and inverted to drive the motor, which in turn drives the water pump through a shaft to pump water. The motor and the water pump work through physical transmission. To investigate the relationship between the motor speed and the inverter input voltage, the load in this design uses a three-phase asynchronous motor, the parameters of which are shown in Table 3. Field-Oriented Control (FOC) is used to achieve precise control of the motor.

[0120] Table 3. Motor Parameters

[0121]

[0122] Fifth Embodiment

[0123] Based on any of the foregoing embodiments, in this embodiment, Figure 9-10 This represents the system's output characteristics in Mode 1. To maintain long-term motor operation, the motor speed must be kept at its rated speed. Therefore, whether each mode can maintain the motor at its rated speed is used as the dividing line, when the irradiance is 750 W / m². 2 At that time, the motor speed is at its rated speed, therefore the irradiance is 750~1000 W / m. 2 At that time, the motor was entirely driven by photovoltaics. In the simulation, the irradiance increased from 1000 to 750 W / m² in 3 seconds. 2 Due to the step change, the photovoltaic output power decreased from 1890 W to 1150 W. The switched-capacitor boost converter has a duty cycle of 0.5, boosting the photovoltaic voltage before inputting it to the inverter. The switched-capacitor structure results in an output voltage that is twice the input voltage, achieving voltage multiplication. Therefore, the inverter input voltage waveform at this time is as follows: Figure 9 As shown in the figure, V PV V is the photovoltaic input voltage. Bat V is the battery input voltage. dc This is the DC-side output voltage (i.e., the inverter topology input voltage).

[0124] The motor speed remains constant at the rated speed, and the waveform changes as follows: Figure 10 As shown.

[0125] Figure 11-12 This represents the system's output characteristics in mode two. Solar irradiance is between 500 and 750 W / m². 2At this time, the motor is driven by a combination of photovoltaic power and battery storage. The output power of the photovoltaic power and battery storage accounts for approximately [percentage missing]. Figure 11 As shown in the figure, P PV For photovoltaic output power, P Bat P is the output power of the battery. 总 This represents the total power output from the photovoltaic system and the battery. Irradiance ranges from 500 to 750 W / m² in 3 seconds. 2 The step change resulted in the photovoltaic output power's share of the total power increasing from 0.65% to 0.97%. The motor speed was as follows... Figure 12 As shown, when the irradiance is 500 W / m 2 The output power ratio of photovoltaic and battery is 0.5 and 0.5 respectively, which is insufficient to enable the motor to operate at its rated speed.

[0126] Figure 13 The figure shows the output characteristics of the system in mode three, where P... PV For photovoltaic output power, P Bat The output power of the battery is given by the efficiency of the photovoltaic power generation through the switching transistor S. a1 With S a2 For battery charging efficiency. Solar irradiance is 185~500 W / m². 2 At times, the combined output of photovoltaic power and battery power is insufficient to drive the motor; therefore, the power output from the photovoltaic system is used to charge the battery. The maximum charging efficiency is 99.73%. When the irradiance is below 185 W / m²... 2 At times, the photovoltaic output is insufficient to charge the battery.

[0127] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0128] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such 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 modules V PV and storage battery V Bat Among them, photovoltaic module V PV and storage battery V Bat The switching transistors Sa1, Sa2, and Sa3 are controlled to switch on / off according to the magnitude of the photovoltaic output voltage, so as to switch their own power supply / discharge mode. A three-port boost inverter topology includes a three-phase inverter and a boost capacitor C connected in parallel at the input of the three-phase full-bridge inverter. o It also includes reverse polarity protection diode VD0, diode VD1, diode VD2, and capacitor C. Bat , switched capacitor C1, inductor L1, inductor L, load, switching transistor Sa1, switching transistor Sa2 and switching transistor Sa3; The three-phase inverter includes switching transistors S1, S2, S3, S4, S5, and S6. The collectors of switching transistors S1, S3, and S5 are connected together and linked to a boost capacitor C. o The positive terminal of the transistor is connected to the emitter of transistors S2, S4, and S6, and a boost capacitor C is connected to it. o The negative electrode of the diode VD0 is connected to the anode of the photovoltaic module V. PV The positive electrode; Capacitor C Bat The positive terminal of the battery is connected to V. Bat The positive terminal and one end of the inductor L1, capacitor C Bat The negative terminal of the battery is connected to V. Bat The negative terminal of the diode is connected to the inductor; the other end of the inductor L1 is connected to one end of the switched capacitor C1, the other end of the switched capacitor C1 is connected to the cathode of the diode VD1 and one end of the inductor L, the other end of the inductor L is connected to the anode of the diode VD2, and the cathode of the diode VD2 is connected to the boost capacitor C. o The positive terminal is connected, and the three phases a, b, and c of the load are connected to the connection points of switch S1 and switch S4, switch S3 and switch S6, and switch S5 and switch S2, respectively. The switching transistors Sa1 and Sa2 are connected in series. The collector of switching transistor Sa1 is connected to the cathode of diode VD0 and the anode of diode VD1, and the emitter of switching transistor Sa2 is connected to the photovoltaic module V. PV The negative terminal of the switch, the emitter of switch Sa1, and the collector of switch Sa2 are connected to the other end of inductor L1; The collector of switching transistor Sa3 is connected to the other end of inductor L and the anode of diode VD2, and the emitter of switching transistor Sa3 is connected to boost capacitor C. o negative electrode, photovoltaic module V PV The negative electrode and battery V Bat The negative electrode.

2. A control method applied to the three-port boost inverter topology as described in claim 1, characterized in that, The control method includes 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 of the photovoltaic module... max At that time, the control three-port boost inverter topology is switched to mode one so that the photovoltaic modules can 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 switched to mode two so that the photovoltaic module and the battery can drive the load together. When the current output voltage is greater than the rated minimum output voltage V of the photovoltaic module min When the voltage is less than or equal to the maximum discharge voltage V1 of the battery, the three-port boost inverter topology is switched to mode three so that the photovoltaic modules can charge the battery.

3. The control method for the three-port boost inverter topology as described in claim 2, characterized in that, The specific steps for controlling the three-port boost inverter topology to switch to mode one include: Upon receiving a high-level control signal, control switch Sa1 and diode VD2 are turned off, while control switches Sa2 and Sa3, along with diodes VD0 and VD1, are turned on, thereby enabling the photovoltaic module V... PV The outflowing current sequentially passes through diode VD0, diode VD1, capacitor C1 and switch S2, inductor L1 and switch S3, and flows back to the negative terminal to form a circuit. Capacitor C1 and switch S2, and inductor L1 and switch 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 control switch Sa1 is turned on with diodes VD0 and VD2, and the control switch Sa2 and Sa3 are turned off with diode VD1, so that current flows through diode VD0, switch Sa1, capacitor C1, inductor L1 and diode VD2, and capacitor C1 and inductor L1 discharge in series.

4. The control method for the three-port boost inverter topology as described in claim 2, characterized in that, The step of controlling the three-port boost inverter topology to switch to mode two specifically includes: Upon receiving a high-level control signal, control switch Sa1 and diode VD2 are turned off, while control switches Sa2 and Sa3, along with diodes VD0 and VD1, are turned on, thereby enabling the photovoltaic module V... PV The output current passes through diode VD0, charging capacitor C1 and inductor L, and also powering battery V. Bat The output current passes through inductor L1 and switching transistor Sa3, charging inductor L1. Upon receiving a low-level control signal, control switches Sa1, Sa2, and Sa3, diode VD0, and diode VD1 are turned off, while control diode VD2 is turned on, so that the battery V... Bat Discharge in series with inductor L, capacitor C1, and inductor L.

5. The control method for the three-port boost inverter topology as described in claim 2, characterized in that, The steps for controlling the three-port boost inverter topology to switch to mode three specifically include: Upon receiving a high-level control signal, control switch Sa1 and diode VD0 are turned on, while control switches Sa2 and Sa3, diodes VD1 and VD2 are turned off, thereby turning off the photovoltaic module V. PV The output current charges the battery through diode VD1 and inductor L1. Upon receiving a low-level control signal, switch Sa3, diodes VD0 and VD1 are turned on, while switch Sa1, switch Sa2, and diode VD2 are turned off, thereby enabling the photovoltaic module V... PV The output current discharges through diode VD0, diode VD1, inductor L1 and switching transistor Sa3.

6. A method for selecting components applied in a three-port boost inverter topology as described in claim 1, characterized in that, The components include switching transistors Sa1, Sa2, and Sa3, diodes VD0, VD1, and VD2, and a photovoltaic module V. PV Storage battery V Bat Switched capacitor C1, inductor L and inductor L1; Among them, switching transistors Sa1, Sa2, and Sa3 correspond to voltage stress V, respectively. Sa1_MAX Voltage stress V Sa2_MAX and voltage stress V Sa3_MAX And the voltage stress V corresponding to diodes VD0, VD1, and VD2 respectively. VD0_MAX Voltage stress V VD1_MAX and voltage stress V VD2_MAX They respectively satisfy: ； In the formula, V PV V is the output voltage of the photovoltaic system. Bat D1 represents the battery output voltage, and D1 represents the mode-duty cycle. Among them, switching transistors Sa1, Sa2, and Sa3 correspond to current stress I, respectively. Sa1_MAX Current stress I Sa2_MAX and current stress I Sa3_MAX And the current stress I corresponding to diodes VD0, VD1, and VD2 respectively. VD0_MAX Current stress I VD1_MAX Current stress I VD2_MAX They respectively satisfy: ； In the formula, I o For the topology output current, I Bat D1 represents the battery output current; D2 and D3 represent the duty cycles of mode two and mode three, respectively. Among them, photovoltaic module V PV With storage battery V Bat Zener capacitor C PV C Bat They respectively satisfy: ； In the formula, I PV with I Bat These are the input currents of the photovoltaic system and the battery, respectively; f sw D1 and D2 are the switching frequency; D1 and D2 are the duty cycles of the boost converter through which the photovoltaic cells and batteries pass, ∆V. PV The ripple current of the photovoltaic module is ∆V. Bat Let be the ripple voltage of the battery, and satisfy: ； In the formula, V in V is the input voltage. out This refers to the output voltage. The capacitance value C1 of the switched capacitor C1 satisfies: ； In the formula, I load This is the load current; Wherein, the inductance value L of inductor L and the inductance value L1 of inductor L1 satisfy the following conditions respectively: ； In the formula, ∆I PV The ripple current of the photovoltaic module is ∆I. Bat The ripple current of the battery must satisfy: 。 7. A component selection result obtained by using the component selection method in the three-port boost inverter topology as described in claim 6.

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