Wireless electric energy transmission system for multi-split charging of electric bicycle

Abstract

The invention relates to the technical field of wireless charging, and particularly discloses a wireless electric energy transmission system for multi-split charging of an electric bicycle, which comprises a direct-current voltage source UD, a high-frequency inverter H, an alternating-current switch Si, a transmitting side LCC compensation network, a magnetic coupler, a receiving side LCC compensation network, a rectifier Di, a filter capacitor CFi and a battery load RBi, an alternating current switch Si, the transmitting side LCC compensation network, the magnetic coupler, the receiving side LCC compensation network, the rectifier Di, the filter capacitor CFi and the battery load RBi form an electric energy output channel, the output channel is connected with the high-frequency inverter H, and the output end of the rectifier Di supplies power to the battery load RBi through the filter capacitor CFi. The beneficial effects of the invention are that the system can achieve the automatic switching of a plurality of output channels from a constant current mode to a constant voltage mode under the condition of no detection and no special control circuit, improves the utilization rate of an inverter, saves an open circuit protection circuit, reduces the cost, and is suitable for the one-to-many charging application of electric bicycles of different specifications.

Description

Technical Field

[0001] The present invention relates to the field of wireless charging technology, and in particular to a wireless power transmission system for charging multiple electric bicycles. Background Art

[0002] With the promotion of green travel concepts and the intensification of urban traffic congestion, electric bicycles have become the mainstream choice for short-distance travel due to their convenience, economy and environmental protection. The number of electric bicycles in China, Southeast Asia and Europe has reached hundreds of millions and continues to grow. Traditional charging methods rely on wired charging piles or dismantling batteries for home charging, which leads to the following problems:

[0003] Safety hazards: Problems such as private wiring, overcharging, and battery short circuits occur frequently and can easily cause fires (according to statistics, more than 80% of electric bicycle fires are caused by improper charging).

[0004] Inefficiency: In centralized charging scenarios (such as residential areas and commercial districts), there is an insufficient number of charging piles and users have to wait in long queues.

[0005] Management challenges: Charging facilities are scattered, cables are cluttered, maintenance costs are high, and it is difficult to meet the charging needs of multiple vehicles at the same time.

[0006] With the rapid development of wireless power transmission technology, wireless power transmission systems have been widely used in the fields of electric vehicle charging, portable electronic device power supply, and IoT terminal energy management. This non-contact power supply method has the advantages of high efficiency, flexibility, and safety, and solves many limitations of traditional cable transmission. However, how to achieve power supply with multiple output specifications in one system and meet the requirements of different loads for constant current and constant voltage modes while ensuring high efficiency is still an important technical challenge.

[0007] Most existing wireless power transmission systems rely on complex control units to switch between different power supply modes. At the same time, the design of several output channels is often accompanied by reduced system efficiency and complicated circuit structure. In addition, in order to deal with abnormal situations such as open loads, special protection circuits are often required, further increasing the cost and complexity of the system. Therefore, the market urgently needs a wireless power transmission system for one-to-many charging of electric bicycles that can simplify circuit design and realize automatic switching between constant current and constant voltage modes of on-board batteries without detection and special control circuits. Summary of the invention

[0008] The present invention proposes a wireless power transmission system for one-to-many charging of electric bicycles to solve the above problems. This system can supply power to a large number of vehicle-mounted batteries of various specifications simultaneously, and can automatically achieve the conversion from constant current to constant voltage mode through the structural characteristics of the circuit itself without being equipped with detection and control circuits. It is convenient to control, simple in structure, low in cost, and stable in operation.

[0009] The technical solution of the present invention is realized as follows:

[0010] A wireless power transmission system for one-to-many charging of electric bicycles includes a DC voltage source U D , a high-frequency inverter H composed of 4 MOSFET switches (Q1, Q2, Q3, Q4), several AC switches S i (i = 1, 2, 3... n), several transmitting-side series compensation inductors L 1i (i = 1, 2, 3... n) , transmitting-side parallel compensation capacitors C P1i (i = 1, 2, 3... n), and transmitting-side series compensation capacitors C P2i (i = 1, 2, 3... n) that form a transmitting-side LCC compensation network, several magnetic couplers composed of transmitting coils L Pi (i = 1, 2, 3... n) and receiving coils L Si (i = 1, 2, 3... n), several receiving-side series compensation inductors L 2i (i = 1, 2, 3... n), receiving-side parallel compensation capacitors C S1i (i = 1, 2, 3... n) and receiving-side series compensation capacitors C S2i (i = 1, 2, 3... n) that form a receiving-side LCC compensation network, several rectifiers D i (i = 1, 2, 3... n), several filter capacitors C Fi (i = 1, 2, 3... n) and several battery loads R Bi (i = 1, 2, 3... n) ;

[0011] An AC switch S i , a transmitting-side LCC compensation network, a magnetic coupler, a receiving-side LCC compensation network, a rectifier D i , a filter capacitor C Fi and a battery load R Bi form a power output channel. The output channel is connected to the high-frequency inverter H. The rectifier D i is composed of four diodes (D 1i , D 2i , D 3i , D 4i), the rectifier D i 's output terminal passes through the filter capacitor C Fi to supply power to the battery load R Bi .

[0012] Furthermore, one DC input terminal of the high-frequency inverter H is connected to the positive pole of the DC voltage source U D , and the other DC input terminal is connected to the negative pole of the DC voltage source U D ;

[0013] One end of the series compensation inductor L 1i on the transmitting side is connected to one end of the output of the high-frequency inverter H through the AC switch S i , and the other end of the series compensation inductor L 1i on the transmitting side is connected to the common terminal of the parallel compensation capacitor C P1i on the transmitting side and the series compensation capacitor C P2i on the transmitting side. The other end of the series compensation capacitor C P2i on the transmitting side is connected to one end of the transmitting coil L Pi . The other end of the transmitting coil L Pi is connected to the common terminal of the parallel compensation capacitor C P1i on the transmitting side and the other output terminal of the high-frequency inverter H;

[0014] One end of the receiving coil L Si is connected to the cathode of the diode D 4i . The other end of the receiving coil L Si is connected to one end of the series compensation capacitor C S2i on the receiving side. The other end of the series compensation capacitor C S2i on the receiving side is connected to the common terminal of the parallel compensation capacitor C S1i on the receiving side and the series compensation inductor L 2i on the receiving side. The other end of the series compensation inductor L 2i on the receiving side is connected to the anode of the diode D 1i . The other end of the parallel compensation capacitor C S1i on the receiving side is connected to the common anode of the diode D 2i and the diode D 4i .

[0015] Furthermore, the LCC compensation network on the receiving side can automatically achieve the switching from constant current to constant voltage of the vehicle-mounted battery.

[0016] Furthermore, the compensation capacitance values C P1i , C P2i , C S1i , C S2i of the output channel are calculated by the formula:

[0017] ;

[0018] where ω is the resonant angular frequency of the system.

[0019] Adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0020] 1. Multiple output channels of the present invention share one inverter, enabling the system to supply power to multiple vehicle-mounted batteries of different specifications simultaneously. In addition, with reasonable parameter design, the system can achieve different current and voltage outputs at each output port through its own structural attributes to facilitate power supply to multiple vehicle-mounted batteries of different specifications simultaneously.

[0021] 2. Relying on its own special structural attributes, the system of the present invention can automatically switch from the constant current mode to the constant voltage mode at each output channel without being equipped with a detection circuit and a control circuit. The system control is simple and has high stability.

[0022] 3. Each output channel of the system of the present invention can operate at zero phase angle, avoiding the introduction of reactive circulating current and ensuring the transmission efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 is the overall system architecture diagram of the present invention;

[0025] Figure 2 is the system architecture diagram of the present invention when operating in the constant current output mode with channel k as an example;

[0026] Figure 3 is the simplified circuit diagram of the present invention when operating in the constant current output mode with channel k as an example;

[0027] Figure 4 is the system architecture diagram of the present invention when operating in the constant voltage output mode with channel k as an example;

[0028] Figure 5 is the simplified circuit diagram of the present invention when operating in the constant voltage output mode with channel k as an example. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0030] As Figure 1 shown, a wireless power transmission system for one-to-many charging of electric bicycles includes a DC voltage source U D , a high-frequency inverter H composed of 4 MOSFET switches (Q1, Q2, Q3, Q4), several AC switches S i (i = 1, 2, 3... n), several transmitting-side series compensation inductors L 1i (i = 1, 2, 3... n) , transmitting-side parallel compensation capacitors C P1i (i = 1, 2, 3... n), and transmitting-side series compensation capacitors C P2i (i = 1, 2, 3... n) that form a transmitting-side LCC compensation network, several magnetic couplers composed of transmitting coils L Pi (i = 1, 2, 3... n) and receiving coils L Si (i = 1, 2, 3... n), several receiving-side series compensation inductors L 2i (i = 1, 2, 3... n), receiving-side parallel compensation capacitors C S1i (i = 1, 2, 3... n) and receiving-side series compensation capacitors C S2i (i = 1, 2, 3... n) that form a receiving-side LCC compensation network, several rectifiers D i (i = 1, 2, 3... n), several filter capacitors C Fi (i = 1, 2, 3... n) and several battery loads R Bi (i = 1, 2, 3... n) ;

[0031] An AC switch S i , a transmitting-side LCC compensation network, a magnetic coupler, a receiving-side LCC compensation network, a rectifier D i , a filter capacitor C Fi and a battery load R Bi form a power output channel, and the output channel is connected to the high-frequency inverter H. The rectifier D i is composed of four diodes (D 1i , D 2i , D 3i , D 4i ), and the rectifier D iThe output terminal is filtered by capacitor C Fi to supply power to the battery load R Bi .

[0032] The compensation capacitance values C P1i , C P2i , C S1i , C S2i of the output channel are calculated by the formula:

[0033] (1);

[0034] where ω is the system resonance angular frequency.

[0035] Taking output channel k as an example, when output channel k receives a charging signal, it is turned on and starts to work. Output channel k first performs constant current output with special LCC-LCC. After reaching the preset charging voltage, output channel k performs constant voltage charging with LCC-S. The system structure diagram of output channel k during constant current output is as shown in Figure 2 and its corresponding simplified circuit diagram is as shown in Figure 3 .

[0036] (2)

[0037] where I Ok is the AC current output by the inverter;

[0038] According to Kirchhoff's voltage law (KVL), the loop voltage equation is listed for the Figure 3 simplified circuit:

[0039] (3)

[0040] where U ik represents the AC voltage output by the high-frequency inverter H, I 1k represents the current flowing through the series inductor L 1k on the transmitting side, I 2k represents the current flowing through the transmitting coil L Pk , I 3k represents the current flowing through the receiving coil L Sk , I 4k represents the current flowing through the equivalent resistance R1, j represents the imaginary unit, and M represents the mutual inductance between the transmitting coil L Pk and the receiving coil L Sk ;

[0041] According to resonance analysis, the system needs to meet the following conditions:

[0042] (4)

[0043] R 1k isFigure 3 The equivalent resistance between points A and O, R 2k is Figure 2 The equivalent resistance between points B and O, combined with the rectifier D k For the circuit structure, the equivalent resistance R 1k and the equivalent resistance R 2k and R Bk The relationship between them is as follows;

[0044] (5)

[0045] Combining equations (3), (4), and (5), we can obtain R 1k and R 2k The voltage relationship between the two ends satisfies U AO =U BO and then the expression of the current is solved:

[0046] (6)

[0047] The effective value I o of the equivalent input current of the rectifier can be obtained through equation (6);

[0048] (7)

[0049] Combining equation (1), the output current I Bk of the rectifier can be obtained;

[0050] (8)

[0051] Observing equation (8), it can be found that the magnitude of the output current I Bk is independent of the load size and can achieve constant current charging. At this time, the input impedance Z ink of the system can be obtained and simplified as:

[0052] (9)

[0053] It can be found through equation (9) that the value of the input impedance Z ink of the output channel k does not contain an imaginary part and shows a pure resistance externally. Therefore, the system can achieve a zero phase angle. Therefore, when the resonance relationship of equation (2) is satisfied, this output channel can achieve a constant current output under zero phase angle operation through a special LCC-LCC structure. This conclusion applies to each output channel.

[0054] The output channel k performs constant voltage charging and works with the LCC-S topology structure as Figure 4 shown, and the dotted part represents the diode D 1k and the diode D 2kIs reverse-biased. The reverse bias of the diode causes the series compensation inductor L on the receiving side 2k , diode D 1k , diode D 2k to be open-circuited. In the constant voltage mode, the system includes a DC voltage source U D , a high-frequency inverter H, a transmitting-side compensation network composed of the series compensation inductor L 1k on the transmitting side, the shunt compensation capacitor C P1k on the transmitting side, the series compensation capacitor C P2k on the transmitting side, the transmitting coil L Pk , a receiving-side compensation network composed of the shunt compensation capacitor C S1k on the receiving side, the series compensation capacitor C S2k on the receiving side, the receiving coil L Sk , a rectifier D k , a filter capacitor C Fk and a load R Bk . The corresponding simplified circuit is as shown in Figure 5 , where the DC voltage source U D and the high-frequency inverter H output the effective value U of the AC voltage ik relationship, and the rectifier output voltage U Bk and the rectifier input voltage effective value U Ok The relationship between them can be expressed as:

[0055] (10)

[0056] According to Kirchhoff's voltage law (KVL) combined with Figure 5 The simplified circuit can obtain equation (11):

[0057] (11)

[0058] The series connection of the shunt compensation capacitor C S1k on the receiving side and the series compensation capacitor C S2k on the receiving side is equivalent to a capacitor C Sk , and the equivalent relationship is as follows;

[0059] (12)

[0060] Among them, U ik represents the AC voltage output by the high-frequency inverter H, I 1k represents the current flowing through the series compensation inductor L 1k on the transmitting side, I 2k represents the current flowing through the transmitting coil L Pk , I 3k represents the current flowing through the receiving coil L Sk , j represents the imaginary unit, and M represents the transmitting coil L Pkand the receiving coil L Sk Mutual inductance with:

[0061] According to the resonance analysis, the system needs to meet the following conditions:

[0062] (13)

[0063] Combining equations (11)-(13), the expression for the current flowing through R 2k can be obtained:

[0064] (14)

[0065] According to equation (14), the output voltage U of the system can be obtained Bk :

[0066] (15)

[0067] It can be seen from equation (15) that the magnitude of does not affect the output voltage U Bk with the load size, so channel k can achieve constant voltage charging. At this time, the input impedance of the system is:

[0068] (16)

[0069] Based on equation (16), when the output channel k performs constant voltage output, the input resistance of the system appears purely resistive externally, proving that this channel can achieve a zero phase angle in the constant voltage mode. Therefore, when condition (13) is satisfied, the channel can achieve both zero phase angle operation and constant voltage output.

[0070] The receiving sides of multiple channels of the system are all connected in a special LCC manner. This special connection method enables the system to automatically achieve the conversion from constant current to constant voltage mode without the need for a detection and control circuit. Each channel of the system implements a constant current mode with zero phase angle operation in an LCC-LCC structure; when the load voltage of each output channel is higher than the voltage value across the parallel capacitor C S1i at both ends, the diodes D 1k and the diode D 2k are reverse-biased, causing the structure of each channel to switch to an LCC-S structure to achieve constant voltage charging under zero phase angle operation.

[0071] The components not described in detail in this article are prior art.

[0072] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A wireless power transmission system for one-to-many charging of electric bicycles, characterized in that: including a DC voltage source U D , a high-frequency inverter H composed of four MOSFET switches (Q1, Q2, Q3, Q4), several AC switches S i , several series compensation inductors L on the transmitting side 1i , parallel compensation capacitors C on the transmitting side P1i , and series compensation capacitors C on the transmitting side P2i to form a transmitting-side LCC compensation network, several transmitting coils L Pi and receiving coils L Si to form a magnetic coupler, several series compensation inductors L on the receiving side 2i , parallel compensation capacitors C on the receiving side S1i and series compensation capacitors C on the receiving side S2i to form a receiving-side LCC compensation network, several rectifiers D i , several filter capacitors C Fi and several battery loads R Bi ; An AC switch S i , a transmitting - side LCC compensation network, a magnetic coupler, a receiving - side LCC compensation network, a rectifier D i , a filter capacitor C Fi and a battery load R Bi constitute a power output channel, and the output channel is connected to a high - frequency inverter H. The rectifier D i is composed of four diodes (D 1i , D 2i , D 3i , D 4i ). The output terminal of the rectifier D i supplies power to the battery load R Fi through the filter capacitor C Bi .

2. The wireless power transmission system for one-to-many charging of electric bicycles according to claim 1, wherein: One DC input terminal of the high-frequency inverter H is connected to the positive pole of the DC voltage source U D and the other DC input terminal is connected to the negative pole of the DC voltage source U D ; The series compensation inductor L on the transmitting side 1i One end of which is connected to one end of the output of the high-frequency inverter H through the AC switch S i The other end of the series compensation inductor L on the transmitting side 1i Is connected to the common end of the parallel compensation capacitor C on the transmitting side P1i And the series compensation capacitor C on the transmitting side P2i The other end of the series compensation capacitor C on the transmitting side P2i Is connected to one end of the transmitting coil L Pi The other end of the transmitting coil L Pi Is connected to the common end of the parallel compensation capacitor C on the transmitting side P1i And the other output end of the high-frequency inverter H; Receiving coil L Si One end of which is connected to the cathode of diode D 4i The other end of receiving coil L Si is connected to one end of receiving-side series compensation capacitor C S2i The other end of receiving-side series compensation capacitor C S2i is connected to the common end of receiving-side parallel compensation capacitor C S1i and receiving-side series compensation inductor L 2i The other end of receiving-side series compensation inductor L 2i is connected to the anode of diode D 1i The other end of receiving-side parallel compensation capacitor C S1i is connected to diode D 2i and the common anode of diode D 4i .

3. The wireless power transmission system for one-to-many charging of electric bicycles according to claim 2, wherein: The receiving-side LCC compensation network can automatically achieve the switching from constant current to constant voltage of the vehicle-mounted battery.

4. A wireless power transmission system for one-to-many charging of electric bicycles according to claim 2, characterized in that: Compensation capacitance value C of the output channel P1i , C P2i , C S1i , C S2i The calculation formula is as follows: ； Where ω is the system resonance angular frequency.

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