Secondary side non-compensated constant voltage output adjustable wireless power transmission compensation topology

Abstract

The application discloses a wireless power transmission compensation topology structure with adjustable constant voltage output of a secondary side without compensation, which comprises a transmitting coil circuit of a primary side, a relay coil circuit and a receiving coil circuit of a secondary side. The application can realize constant voltage output irrelevant to a load under arbitrary coupling without compensation of the secondary side, and different constant voltage output characteristics of the system can be obtained through design of compensation parameters. The application reduces the number of elements of the secondary side circuit as much as possible, only retains necessary receiving coils, does not need additional compensation elements, guarantees light weight, small size and low cost of the receiving side circuit, and is helpful to realize high integration of the secondary side circuit.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transfer technology, and particularly relates to a constant voltage output adjustable wireless power transfer compensation topology with no secondary-side compensation. Background Technology

[0002] Wireless power transfer technology boasts advantages such as safety, convenience, maintenance-free operation, and strong environmental adaptability, making it highly promising for applications in biomedicine, battery charging, and LED lighting. Inductive wireless power transfer, which relies on electromagnetic induction between the primary and secondary coils of a loosely coupled transformer, is the most widely used due to its low operating frequency and high transmission efficiency. To compensate for the significant leakage inductance of the loosely coupled transformer, resonant compensation circuits are typically added to both the primary and secondary sides to obtain a constant voltage output independent of the load, suitable for applications requiring constant voltage power supply, such as motor drives.

[0003] Currently, many compensation topologies can achieve constant voltage output, but this often requires adding one or more resonant compensation components to both the primary and secondary circuits. Considering the portability and mobility of the secondary receiver, there are many limitations on the size and weight of the secondary circuit in the design. To reduce the size and weight of the secondary circuit and improve the power density, the literature "Modeling and analysis of series-none compensation for wireless power transfer systems with a strong coupling, IEEE Transactions on Power Electronics, 34(2), 1209-1215, 2019" studied the S / N compensation technology without any compensation components on the secondary side, realizing a highly integrated constant voltage output scheme at the receiver. However, the voltage gain of this scheme is fixed. Where L P L S Let k be the self-inductance of the primary transmitting coil and the secondary receiving coil, respectively. PS For transmitting coil L P With receiving coil L S The coupling coefficient between the components is crucial. It's evident that once the loosely coupled transformer is given, the output voltage gain of the S / N compensated wireless power transfer system is completely determined, and different output characteristics cannot be obtained through the design of compensation parameters. If the voltage required by the load changes, the loosely coupled transformer must be redesigned to meet the load requirements. Furthermore, the design of loosely coupled transformers is not only constrained by size, weight, cost, and efficiency, but also needs to satisfy specific input-output relationships, making the design process extremely complex and potentially requiring multiple iterations to meet all requirements. Summary of the Invention

[0004] Purpose of the invention: In order to solve the problems existing in the prior art, the present invention provides a constant voltage output adjustable wireless power transmission compensation topology with no secondary side compensation.

[0005] Technical solution: The present invention provides a constant voltage output adjustable wireless power transmission compensation topology with no secondary-side compensation, characterized in that it includes a transmitting coil circuit, a relay coil circuit and a receiving coil circuit, wherein the transmitting coil circuit and the relay coil circuit are primary-side circuits and the receiving coil circuit is a secondary-side circuit.

[0006] Furthermore, the constant voltage output adjustable wireless power transmission compensation topology with no secondary-side compensation as described in claim 1 is characterized in that the transmitting coil circuit includes a voltage source inverter circuit and a transmitting coil L. P The voltage source inverter circuit has a primary-side compensation network, and its DC side is connected to a DC voltage source. The first output terminal of the voltage source inverter circuit is connected to one end of the transmitting coil through the primary-side compensation network, and the other end of the transmitting coil is connected to the second output terminal of the voltage source inverter circuit.

[0007] The relay coil circuit includes an interconnected relay compensation network and a relay coil L. T ;

[0008] The receiving coil circuit includes a secondary coil L. S 1. Rectifier and filter circuit and load; secondary receiving coil L S Both ends are connected to the AC side of the rectifier and filter circuit, and the DC side of the rectifier and filter circuit is connected to the load R. L .

[0009] Furthermore, both the primary-side compensation network and the relay compensation network include compensation capacitors; when G V =λ CV To achieve constant voltage output, the parameters of the compensation capacitor are determined according to the following formula:

[0010]

[0011]

[0012] Where C P C represents the equivalent capacitance of the primary-side compensation network. T M represents the equivalent capacitance value of the relay compensation network, ω is the system operating angular frequency, and M PS For the primary side transmitting coil L P and secondary receiving coil L S Mutual intuition between them, M PT For the primary side transmitting coil L P and relay coil L T Mutual intuition between them, M TSFor the primary side relay coil L T and secondary receiving coil L S Mutual induction between them, λ CV G is the ideal voltage gain determined based on the output voltage required by the load. V The output voltage V of the wireless power transmission system o With input voltage V in The ratio is also known as the DC voltage gain;

[0013] When λ CV =L S / M PS At this time, the relay compensation network uses an open circuit instead of a compensation capacitor, and the relay coil circuit is in an open circuit state.

[0014] When C P Or C T When the value is negative, the compensation capacitor is replaced by an inductor L in the corresponding compensation network. The value of inductor L is:

[0015]

[0016] Among them, when C P When the value is negative, C = C P When C T When the value is negative, C = C T .

[0017] Furthermore, the voltage source inverter circuit is a half-bridge inverter circuit, a full-bridge inverter circuit, a multi-level inverter circuit, or a push-pull inverter circuit.

[0018] Furthermore, the rectifier and filter circuit adopts bridge rectification, full-wave rectification, voltage doubler rectification, or current doubler rectification.

[0019] Beneficial effects:

[0020] (1) The present invention reduces the number of components in the secondary circuit, retains only the necessary receiving coil, and does not require additional compensation components, thus ensuring the light weight, small size and low cost of the receiving circuit, which helps to achieve a high degree of integration of the secondary circuit.

[0021] (2) By adding a compensation element to the primary circuit, the present invention achieves constant voltage output independent of the load, and has no limitation on the tightness of the coupling between the primary and secondary coils, and can also be achieved under non-strong coupling conditions.

[0022] (3) This invention allows for flexible adjustment of input and output voltage gains through the design of compensation parameters, enabling the system to achieve different levels of constant voltage output characteristics. Facing variations in the voltage required by the load, there is no need to redesign the loosely coupled transformer, simplifying the system design process and reducing complexity; and the voltage gain value λ CVRegardless of the degree of coupling of the loosely coupled transformer, it helps to reduce the sensitivity of the system output to changes in coupling and reduce output fluctuations under variable coupling conditions;

[0023] (4) The inverter circuit of the present invention has a series compensation element connected to the AC side, which can be used as a voltage source inverter circuit, further ensuring efficient power transmission and improving system stability after detuning. It has practical significance and can be widely used in various wireless power supply applications. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the topology of the present invention;

[0025] Figure 2 This is a schematic diagram of the wireless power transfer compensation topology of the present invention, which employs a full-bridge inverter circuit and a bridge rectifier filter circuit.

[0026] Figure 3 This is the fundamental equivalent circuit diagram of the wireless power transmission compensation topology of the present invention;

[0027] Figure 4 This is an application example 1 showing the output voltage gain curves under different load conditions;

[0028] Figure 5 This is the operating waveform under different load conditions in Application Example 1, where Figure (a) shows the load resistance R. L Figure (a) shows the waveform at 10Ω, and Figure (b) shows the load resistance R. L The waveform diagram is shown in Figure (c), which shows the working waveform at 20Ω. L The waveform diagram is shown at 40Ω.

[0029] Figure 6 This is the output voltage gain curve under different load conditions in Application Example 2;

[0030] Figure 7 This is the operating waveform under different load conditions in Application Example 2, where Figure (a) shows the load resistance R. L Figure (a) shows the waveform at 10Ω, and Figure (b) shows the load resistance R. L The waveform diagram is shown in Figure (c), which shows the working waveform at 20Ω. L The waveform diagram is shown at 40Ω.

[0031] Figure 8 This is a circuit diagram of a relay coil compensation network consisting of a compensation inductor;

[0032] Figure 9 This is the output voltage gain curve under different load conditions in application example three;

[0033] Figure 10This is the operating waveform under different load conditions in application example three, where Figure (a) shows the load resistance R. L Figure (a) shows the waveform at 10Ω, and Figure (b) shows the load resistance R. L The waveform diagram is shown in Figure (c), which shows the working waveform at 20Ω. L The waveform diagram is shown at 40Ω. Detailed Implementation

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0035] Figure 1 This is a schematic diagram of the wireless power transmission compensation topology based on a three-coil, uncompensated secondary-side constant voltage output adjustable wireless power transmission, which includes a transmitting coil circuit, a relay coil circuit, and a receiving coil circuit. The transmitting coil circuit and the relay coil circuit are the primary-side circuits, and the receiving coil circuit is the secondary-side circuit.

[0036] The transmitting coil circuit includes a voltage source inverter circuit and a transmitting coil L. P The voltage source inverter circuit has a primary-side compensation network, and its DC side is connected to a DC voltage source. The first output terminal of the voltage source inverter circuit is connected to the transmitting coil L via the primary-side compensation network. P One end is connected to the transmitting coil L P The other end is connected to the second output terminal of the voltage source inverter circuit;

[0037] The relay coil circuit includes an interconnected relay compensation network and a relay coil L. T ;

[0038] The secondary circuit includes a secondary coil L. S 1. Rectifier and filter circuit and load; secondary receiving coil L S Both ends are connected to the AC side of the rectifier and filter circuit, and the DC side of the rectifier and filter circuit is connected to the load R. L .

[0039] Both the initial primary-side compensation network and the relay compensation network include compensation capacitors. The initial primary-side compensation network uses compensation capacitors, or several compensation capacitors connected in series / parallel / series-parallel, or several compensation capacitors and inductors connected in series / parallel / series-parallel. The initial relay compensation network uses compensation capacitors, or several compensation capacitors connected in series / parallel / series-parallel, or several compensation capacitors and inductors connected in series / parallel / series-parallel.

[0040] The voltage source inverter circuit can be a half-bridge inverter circuit, a full-bridge inverter circuit, a multi-level inverter circuit, or a push-pull inverter circuit.

[0041] The rectifier and filter circuit adopts bridge rectification, full-wave rectification, voltage doubler rectification, or current doubler rectification.

[0042] Figure 2 A schematic diagram of a wireless power transfer compensation topology employing a full-bridge inverter circuit and a bridge rectifier filter circuit is presented.

[0043] Figure 3 The simplified compensation circuit using fundamental frequency analysis includes the input AC voltage. Primary-side series compensation capacitor C P Primary transmitting coil L P The equivalent capacitance C of the relay compensation T Relay coil L T Secondary receiving coil L S AC equivalent resistance R E Among them, the input AC voltage The square wave voltage v output by the inverter bridge inv The fundamental component satisfies AC equivalent resistance R E For rectifier filter circuit and load R L The equivalent AC resistance satisfies R E =8R L / π 2 Output AC voltage The input voltage v of the secondary rectifier bridge rec The fundamental component, and the output DC voltage V o satisfy: M PS For the primary side transmitting coil L P and secondary receiving coil L S Mutual intuition between them, M PT For the primary side transmitting coil L P and relay coil L T Mutual intuition between them, M TS For the primary side relay coil L T and secondary receiving coil L S Mutual attraction between them.

[0044] Based on KVL, list the voltage equations for each loop:

[0045]

[0046] Where ω is the system's operating angular frequency, and

[0047] After simplifying the above equation, we can obtain Figure 3 The output voltage of the compensation circuit shown With input voltage AC voltage gain ratio G betweenv for:

[0048]

[0049] in,

[0050] The output DC voltage V of the entire wireless power transfer system o With input DC voltage V in DC voltage gain ratio G between V for:

[0051]

[0052] From equation (3), it can be seen that the condition for the system's output voltage to be constant and independent of the load is:

[0053] Z Peq Z Seq +ω 2 M eq 2 =0 (4)

[0054] And at this time the system DC voltage gain value is

[0055]

[0056] As can be seen from equation (5), the voltage gain independent of the load is related to the compensation parameter, and the voltage gain can be adjusted by adjusting the compensation parameter.

[0057] Let the DC voltage gain G V =λ CV , (λ CV Since is a constant coefficient and is independent of the physical parameters of the loosely coupled transformer (theoretically, it can be any value), substituting it into equation (5) and combining it with equation (4) yields the compensation parameters that should satisfy:

[0058]

[0059] Based on the output voltage V o The magnitude of the value determines the required DC voltage gain λ. CV The value of λ is further determined according to equation (6) to determine the required compensation capacitor value, thus achieving a constant output voltage required by the load that is unaffected by load changes. When λ CV =L S / M PS At that time, C T The capacitance C is zero at this time. T An open circuit can be used instead, meaning the relay coil circuit is in an open-circuit state, the current is zero, and it does not participate in resonance. The compensation parameters of the primary-side compensation network satisfy Formula 6.

[0060] When C P Or C T When the value is negative, the compensation capacitor in the corresponding compensation network is replaced with an inductor L. The compensation parameters of the other compensation network satisfy Formula 6. The relationship between the compensation inductance value L and the negative compensation capacitor value C is as follows:

[0061]

[0062] Among them, when C P When the value is negative, C = C P When C T When the value is negative, C = C T .

[0063] One embodiment of the present invention: To verify the feasibility of the present invention, a 12V input wireless power transmission system was used to verify the proposed compensation method based on a three-coil secondary-side uncompensated adjustable constant voltage output. The parameters of the loosely coupled transformer are: primary-side transmitting coil self-inductance L... P =30μH, self-inductance of secondary receiving coil L S =30μH, relay coil self-inductance L T =20μH, the coupling coefficient between any two coils is k PS =0.5,k PT =0.9,k TS =0.45, mutual inductance M PS =15μH,M PT =22.045μH,M TS =11.023μH. The operating frequency (ω / 2π) of the wireless power transfer system is 200kHz. When the required output voltage is 16V, the voltage gain λ CV =1.33, considering the influence of parasitic parameters, and amplifying by a certain margin, let λ CV =1.5, then the primary-side compensation capacitor C can be calculated according to formula (6). P =21.109nF, relay compensation capacitor C T =12.085nF.

[0064] Figure 4 For Example 1, the open-loop gain G under different load conditions V The simulation curve, equivalent load R E The resistance values ​​are 10Ω, 20Ω, and 40Ω, respectively. Simulation results show that the proposed constant-voltage output wireless power transfer compensation method based on a three-coil, uncompensated secondary side has a gain crossover point, which is insensitive to load changes. Furthermore, the gain value after processing the gain crossover point is 1.5, consistent with the design. For this application example, the simulated gain crossover point frequency is 200kHz, consistent with the preset operating frequency.

[0065] Figure 5 An application example is given in the case of load resistor R. L The inverter circuit output voltage v at 10Ω, 20Ω and 40Ω respectively inv Current i inv Relay coil voltage v T Current i T 1. Rectifier circuit input voltage V rec Current i rec and system output DC voltage V o The waveform. Figure 5 (a) in the text is R L The operating waveform is 10Ω. Figure 5 (b) in the text is R L The operating waveform is 20Ω. Figure 5 (c) in the text is R L The waveform is for a 40Ω load. As can be seen from the graph, when the load resistance changes from 10Ω to 40Ω, the output voltage V... o The voltage remained almost stable at around 16.2V, unchanged with the load, achieving constant output voltage. Theoretically, with a voltage gain of 1.5, the ideal output voltage should be 18V. However, considering the influence of parasitic parameters such as the coil resistance of the loosely coupled transformer and the forward voltage drop of the rectifier diodes, the actual output voltage obtained is slightly lower than the theoretical value. In practical designs, it is advisable to appropriately increase the gain value to compensate for the influence of parasitic parameters. Furthermore, i inv Always lagging behind v inv The input impedance of the resonant network is inductive, which helps to achieve soft switching.

[0066] One embodiment of the present invention: when the voltage required by the load changes to 22V, the voltage gain λ CV =1.83, considering a certain margin, let λ CV =2. At this point, the loosely coupled transformer does not need to be replaced; the loosely coupled transformer in Example 1 can continue to be used, with the compensation parameter values ​​adjusted. The primary-side compensation capacitor C is calculated according to formula (6). P =28.145nF, because λ CV Exactly equal to L S / M PS =30 / 15=2, relay compensation capacitor C T =0nF, at which point the relay coil circuit is in an open circuit state.

[0067] Figure 6 Simulation curves of the open-loop gain under different load conditions are presented for Application Example 2. The gain crossover frequency remains at 200kHz, while the ideal gain value at the crossover point is 2, which is consistent with the design.

[0068] Figure 7Application example two is given in the case of load resistor R. L The system operating waveforms are shown at 10Ω, 20Ω, and 40Ω respectively. Figure 7 (a) in the text is R L The operating waveform is 10Ω. Figure 7 (b) in the text is R L The operating waveform is 20Ω. Figure 7 (d) in R L The operating waveform is 40Ω. Because the relay coil circuit is open-circuited, the current i... T It is always zero. As can be seen from the graph, when the load changes, the output voltage V... o It remains almost constant at around 22V, achieving a constant output voltage that does not change with load variations. And i inv Always lagging behind v inv The input impedance of the resonant network is inductive, which helps to achieve soft switching.

[0069] One embodiment of the present invention: when the voltage required by the load changes to 28V, the voltage gain λ CV =2.33, considering a certain margin, let λ CV =2.5. At this point, the loosely coupled transformer from Example 1 can continue to be used, and the required voltage for the load can be achieved by adjusting the compensation parameter values. The primary-side compensation capacitor C is calculated according to formula (6). P =35.181nF, relay compensation capacitor C T = -14.135nF is negative, therefore, according to equation (7), the corresponding compensation inductance L is obtained. CT =44.8μH. Actual circuit as follows: Figure 8 As shown.

[0070] Figure 9 Simulation curves of the open-loop gain under different load conditions are presented for application example three. The gain crossover frequency remains at 200kHz, and the ideal gain value at the crossover point is 2.5, which is in line with expectations.

[0071] Figure 10 Application example three is given in the case of load resistor R. L The system operating waveforms are shown at 10Ω, 20Ω, and 40Ω respectively. Figure 10 (a) in the text is R L The operating waveform is 10Ω. Figure 10 (b) in the text is R L The operating waveform is 20Ω. Figure 10 (c) in the text is R L The operating waveform is 40Ω. As can be seen from the graph, the output voltage V changes with load variations. o It remains almost constant at around 28V, achieving constant output voltage under varying loads. And i inv Always lagging behind vinv The input impedance of the resonant network is inductive, which helps to achieve soft switching.

[0072] from Figures 4 to 10 It can be seen that the proposed compensation method can achieve constant output voltage, and the constant output voltage value can be flexibly adjusted by adjusting the compensation parameters.

[0073] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A constant voltage output adjustable wireless power transfer compensation topology with no secondary-side compensation, characterized in that: It includes a transmitting coil circuit, a relay coil circuit, and a receiving coil circuit, wherein the transmitting coil circuit and the relay coil circuit are primary-side circuits, and the receiving coil circuit is a secondary-side circuit; The transmitting coil circuit includes a voltage source inverter circuit and a transmitting coil L. P The DC side of the voltage source inverter circuit is connected to a DC voltage source, and the first output terminal of the voltage source inverter circuit is connected to one end of the transmitting coil through the primary side compensation network. The other end of the transmitting coil is connected to the second output terminal of the voltage source inverter circuit. The relay coil circuit includes an interconnected relay compensation network and a relay coil L. T ; The receiving coil circuit includes a secondary coil L. S 1. Rectifier and filter circuit and load; secondary receiving coil L S Both ends are connected to the AC side of the rectifier and filter circuit, and the DC side of the rectifier and filter circuit is connected to the load R. L ; Both the primary-side compensation network and the relay compensation network include compensation capacitors; when To achieve constant voltage output, the parameters of the compensation capacitor are determined according to the following formula: ； in This represents the equivalent capacitance value of the primary-side compensation network. This represents the equivalent capacitance value of the relay compensation network, where ω is the system operating angular frequency. Primary-side transmitting coil and secondary receiving coil Mutual feeling between them Primary-side transmitting coil and relay coil Mutual feeling between them Primary relay coil and secondary receiving coil Mutual feeling between them G is the ideal voltage gain determined based on the output voltage required by the load. V The output voltage V of the wireless power transmission system o With input voltage V in The ratio is also known as the DC voltage gain; when At this time, the relay compensation network uses an open circuit instead of a compensation capacitor, and the relay coil circuit is in an open circuit state. when or When the value is negative, an inductor will be used in the corresponding compensation network. Replacement compensation capacitor, inductor The value is: ； Among them, when When it is negative, ,when When it is negative, .

2. The constant voltage output adjustable wireless power transmission compensation topology with no secondary-side compensation according to claim 1, characterized in that, The voltage source inverter circuit can be a half-bridge inverter circuit, a full-bridge inverter circuit, a multi-level inverter circuit, or a push-pull inverter circuit.

3. The constant voltage output adjustable wireless power transmission compensation topology with no secondary-side compensation according to claim 1, characterized in that, The rectifier and filter circuit adopts bridge rectification, full-wave rectification, voltage doubler rectification, or current doubler rectification.

Images