Background
On earth, non-renewable energy sources are quite limited. Solar energy, wind energy, tidal energy and the like are inexhaustible renewable energy sources for human beings, have cleanliness, safety and universality, and play an important role in the long-term energy strategy of the country. Nowadays, the development of large-scale photovoltaic power generation in China has the characteristic of diversification, and in order to promote implementation of innovation-driven development strategy and promote harmonious symbiosis between human beings and nature, China strongly supports the development of the photovoltaic industry, promotes 'photovoltaic +', distributed power generation, photovoltaic poverty alleviation and photovoltaic leaders, and promotes the progress of the photovoltaic power generation technology, the upgrading of the industry and the reduction of the cost. The application of photovoltaic power generation is as large as photovoltaic grid connection, and the shadow of the electronic equipment can be seen as small as common electronic equipment.
The wireless energy transmission technology is a current technology, is visible everywhere in life and has wide application. The charging device is characterized in that a non-contact mode is adopted for energy transmission, so that the wear rate of the charging device is low, the occupied area of a charging area is relatively small, and partial line connection is saved, so that the charging device is easier to maintain.
With the development of new energy technologies and the application of wireless energy transmission technologies in various industries, the combination of photovoltaic power generation and wireless energy transmission gradually draws attention, and the topological structure and the control strategy of the system affect the efficiency and stability of the system, so that the energy conversion structure, the control algorithm and the implementation thereof are more important.
In the published patent technology, named wireless energy transmission receiving circuit and wireless energy transmission system using the same, application No. 201711037142.5, the disclosed wireless energy transmission receiving circuit widens the load regulation range and improves the wireless energy receiving efficiency by using a reconfigurable rectifier having two operation modes of a full-wave rectifier and a voltage doubler, a pre-rectification regulator capable of regulating the magnitude of an induced voltage output, and a control unit. However, the applicant found that the technology is extremely inconvenient to adjust and the energy conversion is not stable enough in the working process in the work of the field all the year round.
Disclosure of Invention
The to-be-solved technical problem of the utility model lies in, solves the problem that improves current photovoltaic power generation wireless energy transmission system energy conversion efficiency and stable work, provides a conversion efficiency is higher, the better synchronous DC-DC converter of control effect, LCC resonance topology and the MPPT control mode based on Lyapunov backstep control.
The utility model has the following concrete scheme:
a photovoltaic power generation wireless energy transmission system is designed,
the energy transmission direction sequentially comprises a photovoltaic side circuit, a wireless energy transmission and emission circuit and a wireless energy transmission and reception circuit; the photovoltaic side circuit comprises a photovoltaic assembly and a synchronous boosting DC-DC converter assembly; the wireless energy transmission transmitting circuit comprises a full-bridge inverter circuit component and the front half part of an LCC-S resonance compensation mechanism; the wireless energy transmission receiving circuit comprises a rear half part of an LCC-S resonance compensation component, a diode rectifying circuit component, a synchronous step-down DC-DC converter component and an electricity load, wherein the synchronous step-up DC-DC converter component comprises a first capacitor C1Said first capacitor C1Is connected with a first inductor L1Said first capacitor C1Is connected with the first NMOS tube VT in parallel at the other side1A second NMOS transistor VT2First NMOS transistor VT1A second NMOS transistor VT2Is connected with a second capacitor C2Constitute a synchronous boost DC-DC converter assembly.
In a specific implementation, the full-bridge inverter circuit component comprises a bridged third NMOS transistor VT3And a fourth NMOS transistor VT4The fifth NMOS transistor VT5And a sixth NMOS transistor VT6。
In one embodiment, the front half of the LCC-S resonance compensation module is the transmitting end, and the front half is the transmitting endA transmitting terminal, a second inductor L2And a third capacitor C3Series connection, a fourth capacitor C4And a third inductor L3Connected in series with a third capacitor C3The second half part of the LCC-S resonance compensation component comprises an output side of the LCC-S resonance compensation structure, and the output side of the LCC-S resonance compensation structure comprises a fourth inductor L4And a fifth capacitor C5Fourth inductance L4And a fifth capacitor C5Series, fourth inductance L4And a third inductor L3Correspondingly arranged, the output side of the LCC-S resonance compensation structure is connected with a diode uncontrolled rectifying circuit in parallel, and the diode uncontrolled rectifying circuit comprises a first diode VD in bridge connection1A second diode VD2A third diode VD3And a fourth diode VD4A sixth capacitor C6The output of the uncontrolled rectifying circuit of the parallel diode passes through a sixth capacitor C6After output, the synchronous buck DC-DC converter component is connected in parallel, and the synchronous buck DC-DC converter comprises a seventh NMOS tube VT7And an eighth NMOS transistor VT8A fifth inductor L5And a seventh capacitance C7And the output side of the synchronous buck DC-DC converter is connected with an electric load in parallel.
In specific implementation, the synchronous boost DC-DC converter assembly and the synchronous buck DC-DC converter assembly are respectively provided with a voltage/current signal acquisition element, signals output by the voltage/current signal acquisition elements are connected to the microcontroller, and the output end of the microcontroller is connected with a control switch to control the first NMOS tube VT1A second NMOS transistor VT2And a seventh NMOS transistor VT7And an eighth NMOS transistor VT8Duty cycle operating state of.
In specific implementation, the seventh NMOS transistor VT of the synchronous boost DC-DC converter assembly7And an eighth NMOS transistor VT8The switch is controlled to be opened and closed in an MPPT control mode based on Lyapunov reverse control.
In specific implementation, power electronic switching devices in the synchronous boost DC-DC converter assembly and the synchronous buck DC-DC converter assembly are full-control devices, and the full-control devices comprise NMOS or N-type IGBT full-control devices.
The photovoltaic power generation wireless energy transmission system comprises the following steps:
(1) the photovoltaic module generates electricity: the photovoltaic module collects energy, the energy is transmitted to the wireless energy transmission and emission circuit, and the voltage is boosted through a synchronous rectification technology to form direct current a;
(2) wireless energy transmission: the direct current a realizes alternating current conversion through a full-bridge inverter circuit to form alternating current b, and the alternating current b forms alternating current c through an LCC-S resonance compensation mechanism;
(3) wireless energy reception: after the alternating current c is converted into direct current d through the diode uncontrolled rectifying circuit, voltage reduction is realized through a synchronous rectifying technology, and the direct current e is formed and then is connected with an electric load;
the synchronous rectification technology is based on a Lyapunov maximum power point tracking mode or a constant voltage/constant current control mode; the mode is selected by setting a wireless energy power output threshold WEOutput power value W of synchronous step-down DC-DC converter assemblyoComparing in real time in the microcontroller if Wo>WEControlling a first NMOS transistor VT of the synchronous boost DC-DC converter assembly1A second NMOS transistor VT2Working at a fixed duty cycle, a seventh NMOS transistor VT in the synchronous buck DC-DC converter assembly7And an eighth NMOS transistor VT8Operating in constant voltage/constant current mode if Wo<WEControlling a seventh NMOS transistor VT in the synchronous buck DC-DC converter assembly7And an eighth NMOS transistor VT8Working at a fixed duty cycle, the first NMOS transistor VT in the synchronous boost DC-DC converter assembly1A second NMOS transistor VT2The switch is controlled to be opened and closed in an MPPT control mode based on Lyapunov reverse control.
In specific implementation, in the maximum power point tracking mode based on Lyapunov, a duty ratio control formula is as follows:
d is the duty cycle of the DC-DC boost converter u
dcFor synchronously boosting the output voltage u across the DC-DC converter assembly
pvIs the voltage across the first capacitor, i
pvFor the photovoltaic module to output current, e
1,e
2Is an error coefficient, constant k
1,k
2>0。
In a specific implementation, in the constant voltage/constant current control mode, when the constant voltage/constant current control mode works in a constant voltage mode, the expected voltage on two sides of the seventh capacitor C7 is subtracted from the actually measured voltage, the expected current on the load side is calculated by the PI controller, the actually measured current is subtracted, the duty ratio of the synchronous DC-DC buck converter component is calculated by the PI controller, when the constant current mode works, the expected current on the load side is directly given, the actually measured current is subtracted, the duty ratio of the synchronous buck DC-DC converter component is calculated by the PI controller, and the final charging voltage is limited while constant current charging is achieved.
In the concrete implementation of the method, the device comprises a base,
for the voltage across the first capacitor i at maximum power of the system
LIs the current flowing through the first inductor, i
L *For a desired value of the first inductor current, a desired value i of the first inductor current is passed
L *=i
pv+k
1e
1C
1。
The beneficial effects of the utility model reside in that:
compared with a diode, the on-resistance of the MOSFET is only dozens of m omega, so that the conduction loss of the follow current tube is greatly reduced in DC-DC conversion, higher conversion efficiency is obtained, meanwhile, the energy multi-stage conversion is adopted, the control complexity is reduced to a certain extent, the LCC resonance topology presents the characteristic of a constant voltage source, the LCC resonance topology has the characteristic of zero input reactive power, the efficiency can be improved, and the maximum power point tracking is more stable due to the application of the MPPT control mode of Lyapunov reverse thrust control. These features and combinations of features are not mentioned in the prior art.
The main research object in the patent technology is a receiving circuit, the structure is simple, the control of the energy receiving circuit is mainly completed by adopting hardware circuits such as a band-gap reference source and a signal generator, but the hardware circuit needs to be modified when the control parameters are modified, and the wireless energy receiving circuit is suitable for a wireless energy receiving system under the general condition.
In the application, the main research objects are a transmitting circuit and a receiving circuit which are connected with a photovoltaic module, the solar photovoltaic module is suitable for occasions of solar power generation, a microcontroller is mainly adopted to complete control of the whole circuit, only the program is needed to be modified when control parameters are modified, and the control mode is flexible.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are presented herein only to illustrate and explain the present invention, and not to limit the present invention.
Example 1
A photovoltaic power generation wireless energy transmission system and a matched transmission method are disclosed, referring to fig. 1 to 10, the system sequentially comprises a photovoltaic side circuit, a wireless energy transmission transmitting circuit and a wireless energy transmission receiving circuit along an energy transmission direction; the photovoltaic side circuit comprises a photovoltaic module and a synchronous boosting DC-DC converter module; the wireless energy transmission transmitting circuit comprises a full-bridge inverter circuit component and the front half part of an LCC-S resonance compensation mechanism; the wireless energy transmission receiving circuit comprises a rear half part of the LCC-S resonance compensation component, a diode rectifying circuit component, a synchronous buck DC-DC converter component and a power load; the synchronous boost DC-DC converter assembly comprises a first capacitor C1First capacitor C1Is connected with a first inductor L1First capacitor C1Is connected with the first NMOS tube VT in parallel at the other side1A second NMOS transistor VT2First NMOS transistor VT1A second NMOS transistor VT2Is connected with a second capacitor C2Constitute a synchronous boost DC-DC converter assembly.
The full-bridge inverter circuit component comprises a bridged third NMOS transistor VT3And a fourth NMOS transistor VT4The fifth NMOS transistor VT5And a sixth NMOS transistor VT6。
The front half part of the LCC-S resonance compensation component is a transmitting end, and a second inductor L is arranged at the transmitting end2And a third capacitor C3Series connection, a fourth capacitor C4And a third inductor L3Connected in series with a third capacitor C3The second half part of the LCC-S resonance compensation component comprises an output side of the LCC-S resonance compensation structure in parallel connection, and the output side of the LCC-S resonance compensation structure comprises a fourth inductor L4And a fifth capacitor C5Fourth inductance L4And a fifth capacitor C5Series, fourth inductance L4And a third inductor L3Correspondingly arranged, the output side of the LCC-S resonance compensation structure is connected with a diode uncontrolled rectifying circuit in parallel, and the diode uncontrolled rectifying circuit comprises a first diode VD in bridge connection1A second diode VD2A third diode VD3And a fourth diode VD4Sixth, sixthCapacitor C6The output of the uncontrolled rectifying circuit of the parallel diode passes through a sixth capacitor C6After output, the synchronous buck DC-DC converter component is connected in parallel and comprises a seventh NMOS tube VT7And an eighth NMOS transistor VT8A fifth inductor L5And a seventh capacitance C7And the output side of the synchronous step-down DC-DC converter component is connected with an electric load in parallel.
The synchronous boost DC-DC converter component and the buck DC-DC converter are internally provided with voltage/current signal acquisition elements, signals output by the voltage/current signal acquisition elements are connected to the microcontroller, and the output end of the microcontroller is connected with the control switch to control the first NMOS tube VT1A second NMOS transistor VT2And a seventh NMOS transistor VT7And an eighth NMOS transistor VT8Duty cycle operating state of.
Seventh NMOS transistor VT of synchronous boost DC-DC converter assembly7And an eighth NMOS transistor VT8The switch is controlled to be opened and closed in an MPPT control mode based on Lyapunov reverse control.
The power electronic switching devices of the synchronous boost DC-DC converter assembly and the synchronous buck DC-DC converter assembly are full-control devices, and the full-control devices comprise NMOS or N-type IGBT full-control devices.
The photovoltaic power generation wireless energy transmission system is used, and comprises the following steps in the working process:
(1) the photovoltaic module generates electricity: the photovoltaic module collects energy, the energy is transmitted to the wireless energy transmission and emission circuit, and the voltage is boosted through a synchronous rectification technology to form direct current a;
(2) wireless energy transmission: the direct current a realizes alternating current conversion through a full-bridge inverter circuit to form alternating current b, and the alternating current b forms alternating current c through an LCC-S resonance compensation mechanism;
(3) wireless energy reception: after the alternating current c is converted into direct current d through the diode uncontrolled rectifying circuit, voltage reduction is realized through a synchronous rectifying technology, and the direct current e is formed and then is connected with an electric load;
wherein, the synchronous rectification technique adoptsIn a Lyapunov maximum power point tracking mode or a constant voltage/constant current control mode; the mode is selected by setting a wireless energy power output threshold WEOutput power value W of synchronous step-down DC-DC converter assemblyoComparing in real time in the microcontroller if Wo>WEControlling a first NMOS transistor VT of a synchronous boost DC-DC converter assembly1A second NMOS transistor VT2Seventh NMOS transistor VT in synchronous buck DC-DC converter module operating at fixed duty cycle7And an eighth NMOS transistor VT8Operating in constant voltage/constant current mode if Wo<WEControlling a seventh NMOS transistor VT in the synchronous buck DC-DC converter assembly7And an eighth NMOS transistor VT8First NMOS transistor VT in synchronous boost DC-DC converter assembly working with fixed duty ratio1A second NMOS transistor VT2The switch is controlled to be opened and closed in an MPPT control mode based on Lyapunov reverse control.
Based on the Lyapunov maximum power point tracking mode, the duty ratio control formula is as follows:
d is the duty cycle of the DC-DC boost converter u
dcFor synchronously boosting the output voltage u across the DC-DC converter assembly
pvIs the voltage across the first capacitor, i
pvFor the photovoltaic module to output current, e
1,e
2Is an error coefficient, constant k
1,k
2>0。
In the constant voltage/constant current control mode, when the constant voltage/constant current control mode works, the expected voltage on the two sides of the seventh capacitor C7 is subtracted from the actually measured voltage, the expected current on the load side is obtained through calculation of the PI controller, the actually measured current is subtracted, the duty ratio of the DC-DC buck converter is obtained through calculation of the PI controller, when the constant current control mode works, the expected current on the load side is directly given, the actually measured current is subtracted, the duty ratio of the synchronous buck DC-DC converter component is obtained through calculation of the PI controller, constant current charging is achieved, and the final charging voltage is limited.
:
For the voltage across the first capacitor i at maximum power of the system
LIs the current flowing through the first inductor, i
L *For a desired value of the first inductor current, a desired value i of the first inductor current is passed
L *=i
pv+k
1e
1C
1。
Fig. 6 is a power variation curve when the environment of the photovoltaic module changes in the MPPT mode, and it is seen from the graph that the control method can quickly respond to tracking of the maximum power point when the environment changes.
FIGS. 7-8 are graphs showing the voltage-current variation in the constant voltage mode, given a given voltage u1 *The actual voltage reached this steady state value over 0.5s, 30V.
FIGS. 9-10 are graphs showing the variation of voltage and current in constant current mode, given a given current i1 *The actual current reaches this steady state value for 2s, 5A. In operation, PI controllers are typically used on charger circuits. The purpose is to limit the final charging voltage while achieving constant current charging. This is achieved by setting two reference parameters, i.e. the desired voltage and the desired current, for controlling the current and the voltage, respectively. In the initial stage of charging, the output voltage is low and does not reach the limit value of the voltage. Therefore, only one control loop, namely the current loop, plays a role, the output current is controlled, and the working mode is constant current output. By the end of charging, the output voltage reaches the limit value of the voltage, at this time, the voltage ring starts to play a role, the output voltage is limited, the current ring loses the role, and the working mode is constant-voltage output. The control object is still an MOS tube, and the control variables are output voltage and current.
Setting charging power value WEOutput power value W of synchronous step-down DC-DC converter assemblyoComparing in real time in the microcontroller if Wo>WEControlling the first NMOS transistor of the DC-DC boost converterVT1, the second NMOS transistor VT2 works with fixed duty ratio, and the seventh NMOS transistor VT in the synchronous step-down DC-DC converter component7And an eighth NMOS transistor VT8Operating in constant voltage/constant current mode if Wo<WEAnd a seventh NMOS transistor VT in the synchronous step-down DC-DC converter component is controlled7And an eighth NMOS transistor VT8Working at a fixed duty cycle, and during the working process, synchronously boosting the first NMOS transistor VT of the DC-DC converter assembly1A second NMOS transistor VT2The switch is controlled to be opened and closed in an MPPT control mode based on Lyapunov reverse control.
In the course of the work, photovoltaic module is because the change of environment, and output is unsettled, and the load of receiving part has a maximum power that can bear, can not exceed this power in the course of the work, so the design of this application makes output originally when not enough, just sets up work and keeps this maximum power at MPPT control mode this moment, has exceeded this power and has just directly controlled present voltage and current size, has controlled the voltage and current size and has just also restricted the power of output.
In the application, a synchronous DC-DC converter assembly is adopted in a direct-current chopper circuit of a photovoltaic power generation wireless energy transmission system, an energy transmission part adopts an LCC resonance topology, and a photovoltaic side adopts an MPPT control technology based on Lyapunov reverse thrust control, so that the energy transmission efficiency is greatly improved.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing embodiments, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.