Constant-voltage and constant-current output control method based on optical storage wireless power transmission system

Abstract

The invention discloses a constant-voltage constant-current output control method based on an optical storage wireless power transmission system, and relates to the technical field of optical storage wireless power transmission. The system comprises a photovoltaic circuit module, an energy storage module, a wireless transmitting module and a wireless receiving module, the photovoltaic circuit module comprises a solar photovoltaic panel and a DC-DC boost circuit. The energy storage module comprises a storage battery and a bidirectional DC-DC circuit; the wireless transmitting module comprises a full-bridge high-frequency inverter circuit and an LCC resonance compensation circuit. The wireless receiving module comprises an LCC resonance compensation circuit, a full-bridge rectifier module and a load; according to the invention, a wireless electric energy transmission part adopts an LCC-LCC compensation structure, so that the wireless electric energy transmission part has a constant current characteristic, and when the bus voltage is constant, a receiving end has a uniquely determined current value corresponding to the constant current value, so that a wireless system can realize two output modes of constant current output and constant voltage output by adjusting the bus voltage in real time by using a storage battery and a bidirectional DC-DC in the energy storage module.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical storage and wireless power transmission, and in particular relates to a constant voltage and constant current output control method based on an optical storage and wireless power transmission system. Background Art

[0002] With the gradual depletion of fossil energy, the production and utilization of new energy sources are receiving more and more attention. Photovoltaic power generation is a promising direction in the field of new energy. Photovoltaic energy storage systems are mainly used to solve the problem that photovoltaic power generation is easily affected by the environment. In terms of power transmission, the main method used is still the electrical wire connection. Wired power transmission is prone to safety issues such as contact sparks and mechanical wear when plugging and unplugging contacts, while wireless power transmission systems can solve this problem. Therefore, the photovoltaic storage wireless power transmission system has become a hot topic of research at this stage.

[0003] Wireless power transmission systems usually have two output modes: constant voltage and constant current output. The main compensation structures are divided into four basic types, namely series-series (SS), series-parallel (SP), parallel-series (PS) and parallel-parallel (PP). In addition to the basic topology, researchers have also proposed some hybrid topologies, among which the LCL compensation network can not only realize that the compensation capacitor is independent of the load, but also realize that the primary coil current is independent of the load, thus achieving the decoupling of the primary and secondary sides. The LCC compensation network inherits the advantages of the LCL network and can also adjust the primary auxiliary inductance according to demand, thus increasing the freedom of system design. Each structure has its own different characteristics, so it needs to be selected according to our needs.

[0004] In order to achieve constant voltage and constant current output, domestic and foreign experts have proposed many methods, which can be summarized into the following categories: ① control strategy, ② system topology, ③ frequency adjustment. However, no matter which method is used to achieve constant current or constant voltage output, it involves the communication problem between the primary side and the secondary side. In the high-frequency and high-magnetic environment, the addition of the communication module increases the complexity of the system to a certain extent and reduces the stability of the system. The control method proposed in this system is to cooperate with the previous stage of the light storage circuit to achieve constant voltage and constant current control. Summary of the invention

[0005] The purpose of the present invention is to provide a constant voltage and constant current output control method based on a photovoltaic wireless power transmission system to solve the problem that the traditional method mentioned in the above background technology is too complicated to control the constant voltage and constant current and the system is unstable.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A photovoltaic storage and wireless power transmission system capable of realizing constant voltage and constant current control, characterized in that: it comprises a photovoltaic power generation circuit, an energy storage circuit, a wireless power transmission transmitting end, a wireless power transmission receiving end, and energy transmission between the transmitting end and the receiving end is performed through a mutual inductance coil;

[0008] The photovoltaic power generation circuit includes a solar photovoltaic panel and a DC-DC boost circuit;

[0009] The energy storage circuit includes a battery and a bidirectional DC-DC circuit;

[0010] The wireless power transmission transmitting end includes a full-bridge high-frequency inverter circuit and a front side of an LCC-LCC resonant compensation circuit;

[0011] The wireless power transmission receiving end includes a rear side of an LCC-LCC resonance compensation circuit, a full-bridge rectifier circuit and a load.

[0012] In the DC-DC boost circuit described in the above scheme, the capacitor C1 is connected in parallel at both ends of the photovoltaic panel, one side of which is connected to the front end of the series inductor L1, the rear end of the series inductor is connected to the collector of the MOS tube S1 and the front end of the diode D1, the rear end of the diode D1 is connected to one side of the parallel capacitor C2 on the output side of the boost circuit, and the other side of the capacitor C1 is connected to the emitter of the MOS tube S2 and the other side of the capacitor C2 to form a boost circuit.

[0013] In the bidirectional DC-DC circuit described in the above scheme, the series inductor L2 is connected to the drain of the MOS transistor S1 and the source of the MOS transistor S2. The source of the MOS transistor S1 and the drain of the MOS transistor S2 are connected in parallel to the two ends of the above capacitor C2.

[0014] The high-frequency inverter circuit described in the above scheme is composed of silicon carbide S3, S4, S5, and S6;

[0015] The wireless power transmission transmitting end is connected by the upper end of the series compensation inductor L3 and the parallel compensation capacitor C3, and the front end of the series compensation capacitor C4, and the rear end of the series compensation capacitor C4 and the lower end of the parallel compensation capacitor are connected to the transmitting coil.

[0016] The wireless power transmission receiving end described in the above scheme is connected by the upper ends of the series compensation capacitor C5 and the parallel compensation capacitor C6, connected to the front end of the series compensation inductor L4, and the rear end of the series compensation inductor L4 and the parallel compensation capacitor C6 are connected to the full-bridge rectifier circuit behind;

[0017] The full-bridge rectifier circuit is composed of diodes D2, D3, D4 and D5.

[0018] In the above scheme, since the LCC-LCC resonant circuit is in constant current working mode, its current is only related to the bus input voltage. By deriving the voltage-current relationship of the proposed wireless system, the expression of the load current I is obtained as follows:

[0019]

[0020] Among them, M is the mutual inductance of the transmitting and receiving coils of the wireless power transmission system, Uac is the output voltage after inversion, ω is the system resonant frequency, L3 is the series compensation inductance value of the transmitting end, and L4 is the series compensation inductance value of the receiving end.

[0021] When the system needs to achieve constant voltage output, for example, a constant voltage value of U is required, the resistance value can be used to According to the formula The voltage value required by the system at this time is obtained, and the energy storage circuit is used to implement voltage regulation so that the system works in a constant voltage output mode.

[0022] The beneficial effects of the present invention are:

[0023] 1. Compared with the traditional single wireless system, the addition of a photovoltaic storage unit allows the use of clean energy, avoiding air pollution caused by the use of fossil fuels. The addition of a storage battery allows the electricity generated by the photovoltaic panel to be recovered when the wireless system is not fully used, thereby improving energy utilization efficiency. Moreover, when the weather is bad, if the energy output by the photovoltaic panel is insufficient, the storage battery can supplement the energy, thus avoiding the situation where the wireless system cannot operate normally due to insufficient power, thereby improving the stability of the system.

[0024] 2. Compared with the existing control technology, the control method is simple. The voltage and current sampled at the load are calculated to obtain the current load resistance. The bus voltage is controlled according to the inferred voltage-current relationship to achieve the switching of constant voltage and constant current control. There is no need to modify the hardware parameters of the circuit. The control method is flexible, no additional devices are added to the structure of the wireless system, and the system efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a block diagram of the optical storage and wireless power transmission system;

[0026] Figure 2 It is a photovoltaic boost circuit;

[0027] Figure 3 It is a bidirectional DC-DC circuit for energy storage;

[0028] Figure 4 It is the transmitting circuit of the wireless power transmission system;

[0029] Figure 5It is a receiving circuit of a wireless power transmission system;

[0030] Figure 6 This is the waveform of the bus voltage in the variable load constant current control mode;

[0031] Figure 7 This is the output voltage and current waveform of the variable load constant current control mode;

[0032] Figure 8 This is the bus voltage waveform diagram in variable load constant voltage control mode;

[0033] Fig. 9 This is the output voltage and current waveform of the variable load constant voltage control mode; DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1:

[0036] like Figure 1 As shown, the optical storage and wireless power transmission system includes a photovoltaic circuit module, an energy storage module, a wireless transmission module and a wireless receiving module; the photovoltaic circuit module includes a solar photovoltaic panel and a DC-DC boost circuit; the energy storage module includes a battery and a bidirectional DC-DC circuit; the wireless transmission module includes a full-bridge high-frequency inverter circuit and an LCC resonant compensation circuit; the wireless receiving module includes an LCC resonant compensation circuit, a full-bridge rectifier module and a load.

[0037] like Figure 2 As shown, the photovoltaic measurement circuit includes a first filter capacitor C1, a second filter capacitor C2, a first inductor L1, a MOS tube S1 and a diode D1. The boost circuit boosts the low voltage emitted by the photovoltaic panel to supply the wireless system and load behind it, and is also used as a control circuit for MPPT. The switching signal of the MOS tube S1 is controlled by the disturbance observation method.

[0038] like Figure 3As shown, the energy storage circuit includes a second inductor L2, a MOS tube S2, and a MOS tube S3, and shares a second filter capacitor C2 with the boost circuit. The battery side does not need to add a new capacitor due to its own voltage stabilization characteristics. The bidirectional DC-DC circuit can realize the bidirectional flow of energy in the battery and the wireless system. The switching signals of the MOS tube S2 and the MOS tube S3 are controlled by PI, and complementary PWM signals are output. When the bus voltage is higher than the voltage required by the system, the bidirectional DC-DC works in a buck charging mode, and when the bus voltage is lower than the voltage required by the system, the bidirectional DC-DC circuit works in a boost discharge mode.

[0039] like Figure 4 As shown, the transmitting end of the wireless power transmission system includes a high-frequency inverter circuit composed of MOS tubes S4, MOS tubes S5, MOS tubes S6, and MOS tubes S7, and an LCC compensation structure composed of a series compensation inductor L3, a parallel compensation capacitor C3, and a series compensation capacitor C4. Energy enters from the inverter side, and the electric energy is converted from the DC emitted by the photovoltaic panel into AC and transmitted to the receiving end through the LCC resonant circuit.

[0040] like Figure 5 As shown, the receiving end of the wireless power transmission system includes an LCC compensation structure, which is composed of a series compensation capacitor C5, a parallel compensation capacitor C6, and a series compensation inductor L4. The rectifier circuit is composed of a diode D2, a diode D3, a diode D4, and a diode D5. After the energy comes in from the receiving end, it passes through the LCC resonant circuit and enters the rectifier, converting the energy from AC to DC for use by the load.

[0041] The specific constant voltage and constant current output control method based on the optical storage and wireless power transmission system is as follows:

[0042] In order to better analyze the circuit, the equivalent resistance of the high-frequency inverter circuit composed of four MOS tubes S1, S2, S3, and S4 is regarded as R LCC , equivalent AC voltage source U L , the equivalent resistance of the rectifier circuit composed of four diodes D1, D2, D3, and D4 and the subsequent load is regarded as R eqL , R 1L , R 2L is the resistance of the primary coil and the secondary coil, R L3 , R C3 , R C4 is the internal resistance of the primary series compensation inductor, parallel compensation capacitor, and series compensation capacitor, R C5 , R C6 , R L4is the internal resistance of the primary series compensation capacitor, parallel compensation capacitor, and series compensation inductor. I1, I2, I3, and I4 are the phasor forms of the branch currents i1, i2, i3, and i4 of the primary series compensation inductor, primary coil, secondary coil, and secondary series compensation inductor. M is the mutual inductance between coils, and the resonant angular frequency is ω L , the voltage-current relationship of the wireless system is derived as follows:

[0043] according to Figure 1 The circuit model shown and Kirchhoff's law can obtain the equivalent circuit loop equation of the wireless system:

[0044]

[0045] The resonance condition of the LCC-LCC structure is:

[0046]

[0047] Combining equation (1) and equation (2), we can get the expression of each element in the coefficient matrix:

[0048]

[0049] d=-jω L M (6)

[0050]

[0051] The currents in each branch are:

[0052]

[0053] Ideally, the power supply equivalent resistance R LCC , load equivalent resistance R eqL And the internal resistance R of each capacitor and inductor 1L , R 2L , R L3 , R C3 , R C4 , R C5 , R C6 , R L4 is 0, and the current in each branch is:

[0054]

[0055] At this time, the load current is only related to the power supply voltage U L , working angular frequency ω L, coil mutual inductance M, and series-parallel compensation inductance and capacitance. Even if the load size changes, the current will not change suddenly. Therefore, now we only need to monitor the load resistance and then adjust the power supply voltage according to the voltage-current relationship, that is, to control the current by real-time control of the bus voltage.

[0056] like Figure 6 and Figure 7 As shown, in constant current mode, the bus voltage remains basically unchanged, maintained at about 103V. As the load changes, the load current does not change, while the load voltage increases accordingly, realizing the constant current output mode.

[0057] like Figure 8 and Fig. 9 As shown, in constant voltage mode, when the load size changes, the voltage size that needs to keep the current unchanged is calculated through the formula, and then the bus voltage size is adjusted by the energy storage bidirectional DC-DC circuit, so that when the load size changes, the voltage is kept unchanged and maintained at about 90V, while the current changes accordingly to achieve constant voltage output mode. By designing the voltage and current of the bus, the constant voltage value or constant current value required by the load can be met.

[0058] The above description is only used to help understand the method of the present invention and its core essence, but the protection scope of the present invention is not limited thereto. The above implementation is the preferred technical solution of the present invention, but does not limit the protection scope of the present invention. For those skilled in the art in this technical field, equivalent replacement or change according to the technical solution and inventive concept of the present invention within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A light-storage wireless power transmission system capable of achieving constant voltage and constant current control, characterized in that: It includes a photovoltaic power generation circuit, an energy storage circuit, a wireless power transmission transmitter, a wireless power transmission receiver, and energy transmission between the transmitter and the receiver through a mutual inductance coil; The photovoltaic power generation circuit includes a solar photovoltaic panel and a DC-DC boost circuit; The energy storage circuit includes a battery and a bidirectional DC-DC circuit; The wireless power transmission transmitting end includes a full-bridge high-frequency inverter circuit and a front side of an LCC-LCC resonant compensation circuit; The wireless power transmission receiving end includes a rear side of an LCC-LCC resonance compensation circuit, a full-bridge rectifier circuit and a load.

2. The constant voltage and constant current controlled optical storage and wireless power transmission system as claimed in claim 1, characterized in that: In the DC-DC boost circuit, the capacitor C1 is connected in parallel at both ends of the photovoltaic panel, one side of which is connected to the front end of the series inductor L1, the rear end of the series inductor is connected to the drain of the MOS tube S1 and the front end of the diode D1, the rear end of the diode D1 is connected to one side of the parallel capacitor C2 on the output side of the boost circuit, and the other side of the capacitor C1 is connected to the source of the MOS tube S1 and the other side of the capacitor C2 to form a boost circuit.

3. The constant voltage and constant current controlled optical storage and wireless power transmission system as claimed in claim 1, characterized in that: In the bidirectional DC-DC circuit, the series inductor L2 is connected to the drain of the MOS transistor S2 and to the source of the MOS transistor S3. The source of the MOS transistor S2 and the drain of the MOS transistor S3 are connected in parallel to the two ends of the capacitor C2.

4. The constant voltage and constant current controlled optical storage and wireless power transmission system as claimed in claim 1, characterized in that: The high-frequency inverter circuit is composed of silicon carbide S4, S5, S6, and S7; The wireless power transmission transmitting end is connected by the upper end of the series compensation inductor L3 and the parallel compensation capacitor C3, and the front end of the series compensation capacitor C4, and the rear end of the series compensation capacitor C4 and the lower end of the parallel compensation capacitor are connected to the transmitting coil.

5. The constant voltage and constant current controlled optical storage and wireless power transmission system as claimed in claim 1, characterized in that: The wireless power transmission receiving end is connected by the upper ends of the series compensation capacitor C5 and the parallel compensation capacitor C6, connected to the front end of the series compensation inductor L4, and the rear end of the series compensation inductor L4 and the parallel compensation capacitor C6 are connected to the full-bridge rectifier circuit behind; The full-bridge rectifier circuit is composed of diodes D2, D3, D4 and D5.

6. The constant voltage and constant current controlled optical storage and wireless power transmission system as claimed in claim 1, characterized in that: Since the LCC-LCC resonant circuit is in constant current working mode, its current is only related to the bus input voltage. By deriving the proposed wireless system voltage-current relationship, the expression of the load current I is obtained as follows: Among them, M is the mutual inductance of the transmitting and receiving coils of the wireless power transmission system, Uac is the output voltage after inversion, ω is the system resonant frequency, L3 is the series compensation inductance value of the transmitting end, and L4 is the series compensation inductance value of the receiving end.

7. The constant voltage and constant current controlled optical storage and wireless power transmission system as claimed in claim 6, characterized in that: When the system needs to achieve constant voltage output, for example, a constant voltage value of U is required, the resistor value can be used to According to the formula The voltage value required by the system at this time is obtained, and the energy storage circuit is used to implement voltage regulation so that the system works in a constant voltage output mode.

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