Lcc-s compensation network and wireless power transmission system and compensation method

Abstract

The application provides an LCC-S compensation network, a wireless power transmission system and a compensation method. The compensation method comprises the following steps: constructing a basic transmission matrix equivalent model, determining the zeroing condition of the matrix coefficients in the basic transmission matrix equivalent model; creating an LCC-S compensation network transmission matrix equivalent model, and after corresponding zeroing processing of the matrix coefficients according to the zeroing condition, the relationship between the frequency-adjusted inductance, the frequency-adjusted capacitance, the primary capacitance, the secondary capacitance and the tuning frequency is obtained to determine the resonance condition, and then the target LCC-S compensation network is obtained, and the constant voltage and zero phase angle output compensation are carried out based on the target LCC-S compensation network. The application constructs the LCC-S compensation network in the form of a matrix model from the mathematical calculation and the circuit characteristics, analyzes the related compensation conditions of the coupling resonance stable output in the wireless power transmission system by means of the assumption method, and sets the compensation network and the compensation method reasonably to realize the constant voltage output irrelevant to the mutual inductance.

Description

Technical Field

[0001] This invention relates to the field of wireless charging technology, specifically to an LCC-S compensation network and a wireless power transmission system and compensation method. Background Technology

[0002] Wireless charging technology has broad application prospects in fields such as implantable medical devices, mobile phones and portable wearable devices, and electric vehicles. Wireless Power Transmission Systems (WPTS) can eliminate wiring and contact installation problems, and there are no exposed conductors. The energy transmission capability is not affected by factors such as water and pollutants, improving the reliability and safety of the equipment. The various parts of the system are independent of each other, avoiding unnecessary electrical and mechanical damage, saving wiring and maintenance costs, and improving energy utilization.

[0003] Generally, wireless power transfer systems (WPTS) are loosely coupled systems. Due to the large number of energy storage components and the complexity of closed-loop control, most WPTS currently operate in an open-loop state, achieving the required functions through a reasonable compensation network. To effectively extend the lifespan of the energy storage battery and ensure battery charging and usage safety, the current applications in charging systems mainly focus on constant current (CC) and constant voltage (CV) outputs. Simultaneously, it is necessary to achieve zero phase angle (ZPA) and resonance conditions independent of mutual inductance as much as possible. This characteristic of resonance conditions being independent of mutual inductance is particularly suitable for application in dynamic wireless charging.

[0004] Existing technologies generally employ single-capacitor compensation topologies and SS-type compensation methods. Although the SS-type compensation method has significant advantages over other compensation methods, it also suffers from the drawback that the output power drops sharply when the mutual inductance increases. Moreover, neither the single-capacitor compensation topology nor the SS-type compensation method can achieve CV output that is independent of the resonant condition and the mutual inductance M. Summary of the Invention

[0005] In view of this, it is necessary to provide an LCC-S compensation network and a wireless power transfer system and compensation method, which can be constructed from the perspective of mathematical calculation and circuit characteristics to achieve CV output that is independent of the resonance condition and the mutual inductance M.

[0006] To achieve the above objectives, in one respect, the present invention provides an LCC-S compensation network, comprising: The system includes an input port, an output port, and a compensation circuit; the input port includes a positive input terminal and a negative input terminal, and the output port includes a positive output terminal and a negative output terminal. The compensation circuit includes a frequency-modulated inductor, a frequency-modulated capacitor, a primary capacitor, a primary equivalent inductance, a mutual inductance, a secondary equivalent inductance, and a secondary capacitor. One end of the frequency-modulated inductor is connected to the positive input terminal, and the other end of the frequency-modulated inductor is connected to one end of the frequency-modulated capacitor and one end of the primary capacitor. The other end of the frequency-modulated capacitor is connected to the negative input terminal. The other end of the primary capacitor is connected to one end of the primary equivalent inductance. The other end of the primary equivalent inductance is connected to one end of the mutual inductance and one end of the secondary equivalent inductance. The other end of the mutual inductance is connected to the negative output terminal. The other end of the secondary equivalent inductance is connected to one end of the secondary capacitor, and the other end of the secondary capacitor is connected to the positive output terminal. When the input port is connected to a constant voltage source or a constant current source, the constant voltage and zero phase angle output of the load connected to the output port can be achieved by adjusting the values ​​of the frequency modulation inductor, frequency modulation capacitor, primary capacitor and secondary capacitor, without being related to mutual inductance.

[0007] In some possible implementations, the LCC-S compensation network further includes: a primary-side coil resistor and a secondary-side coil resistor; one end of the primary-side coil resistor is connected to the primary-side capacitor, and the other end of the primary-side coil resistor is connected to the primary-side equivalent inductance; one end of the secondary-side coil resistor is connected to the secondary-side capacitor, and the other end of the primary-side coil resistor is connected to the secondary-side equivalent inductance.

[0008] In some possible implementations, the circuit positions of the frequency modulation inductor and the frequency modulation capacitor are swapped in the compensation circuit.

[0009] In some possible implementations, the circuit position of the frequency modulation inductor and frequency modulation capacitor in the compensation circuit is adjusted to be between the secondary capacitor and the output port.

[0010] In some possible implementations, the circuit positions of the frequency modulation inductor and the frequency modulation capacitor located between the secondary capacitor and the output port are swapped in the compensation circuit.

[0011] To achieve the above objectives, in another aspect, the present invention also provides a wireless power transmission system, which includes the LCC-S compensation network as described above, a constant current source or a constant voltage source, and a load; the constant current source or constant voltage source is connected to the input port, and the load is connected to the output port; Specifically, constant voltage and zero phase angle output of the load are achieved under conditions unrelated to mutual inductance by adjusting the values ​​of the frequency modulation inductor, frequency modulation capacitor, primary capacitor, and secondary capacitor.

[0012] To achieve the above objectives, the present invention also provides a constant voltage and zero phase angle output compensation method, based on the aforementioned LCC-S compensation network, or, as described above, a wireless power transmission system; the compensation method includes: A basic transmission matrix equivalent model is constructed based on a reciprocal two-port network, and the zeroing of matrix coefficients in the basic transmission matrix equivalent model is determined under the condition of constant voltage input or constant current input and constant voltage and zero phase angle output, which is independent of mutual inductance. Based on the basic transmission matrix equivalent model, the LCC-S compensation network is modeled to obtain the LCC-S compensation network transmission matrix equivalent model. After setting the matrix coefficients of the LCC-S compensation network transmission matrix equivalent model to zero according to the zeroing situation of the matrix coefficients in the basic transmission matrix equivalent model, the relationship between the frequency modulation inductor, frequency modulation capacitor, primary side capacitor, secondary side capacitor and tuning frequency is obtained. The resonance condition is determined based on the relationship between the frequency-modulated inductor, frequency-modulated capacitor, primary-side capacitor, secondary-side capacitor, and tuning frequency. Substitute the matrix coefficients corresponding to the resonance condition into the equivalent model of the LCC-S compensation network transmission matrix to obtain the target LCC-S compensation network, and perform constant voltage and zero phase angle output compensation based on the target LCC-S compensation network.

[0013] In some possible implementations, determining the zeroing of matrix coefficients in the equivalent model of the basic transmission matrix under constant voltage or constant current input conditions and maintaining constant voltage and zero phase angle output independent of mutual inductance includes: When the input voltage is constant, if it is necessary to keep it independent of mutual inductance, the matrix coefficients related to the mutual inductance value are set to zero. If it is necessary to keep the output voltage constant, the matrix coefficients related to the output current in the voltage source expression are set to zero. If it is necessary to keep the output voltage zero, the matrix coefficients related to the output voltage in the current source expression are set to zero. When a constant current is input, if it is necessary to maintain independence from mutual inductance, the matrix coefficients related to the mutual inductance value are set to zero. If it is necessary to maintain a constant voltage output, the matrix coefficients related to the output current in the current source expression are set to zero. If it is necessary to maintain a zero phase angle output, the matrix coefficients related to the output voltage in the voltage source expression are set to zero.

[0014] In some possible implementations, after zeroing the matrix coefficients of the LCC-S compensation network transmission matrix equivalent model according to the zeroing status of the matrix coefficients in the basic transmission matrix equivalent model, the relationship between the frequency modulation inductor, frequency modulation capacitor, primary-side capacitor, secondary-side capacitor, and tuning frequency is obtained, including: When a constant voltage input is applied, the matrix coefficients related to the mutual inductance value are set to zero to obtain the relationship between the frequency-modulated inductor, frequency-modulated capacitor, and tuning frequency. The matrix coefficients related to the output current in the voltage source expression are set to zero to obtain the relationship between the frequency-modulated inductor, frequency-modulated capacitor, primary-side capacitor, secondary-side capacitor, and tuning frequency. The matrix coefficients related to the output voltage in the current source expression are set to zero to obtain the relationship between the frequency-modulated inductor, frequency-modulated capacitor, primary-side capacitor, and tuning frequency.

[0015] In some possible implementations, the method further includes: Determine the input-output gain and input impedance when the input is constant voltage or constant current and the output is constant voltage and zero phase angle under conditions independent of mutual inductance; Determine the input apparent power and input-output efficiency when the input is constant voltage or constant current and the output is constant voltage and zero phase angle under conditions independent of mutual inductance.

[0016] The beneficial effects of this invention are: This invention starts from mathematical calculations and circuit characteristics, constructs an LCC-S compensation network in the form of a matrix model, analyzes the relevant compensation conditions for the stable output of coupled resonance in a wireless power transmission system through the assumption method, and achieves constant voltage output with resonance conditions independent of mutual inductance by reasonably setting the compensation network and compensation method.

[0017] Furthermore, this invention also provides a general method for calculating the CC output, CV output, ZPA condition, voltage gain Gvv, and current gain Gvi of the compensation network, providing a solid theoretical foundation for subsequent compensation network construction. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the structure of the first embodiment of the LCC-S compensation network provided by the present invention; Figure 2 A schematic diagram of the LCC-S compensation network considering coil resistance provided by the present invention; Figure 3 A schematic diagram of the structure of the second embodiment of the LCC-S compensation network provided by the present invention; Figure 4 This is a schematic diagram of the third embodiment of the LCC-S compensation network provided by the present invention; Figure 5This is a schematic diagram of the fourth embodiment of the LCC-S compensation network provided by the present invention; Figure 6 A schematic diagram of the structure of an embodiment of the basic transmission matrix equivalent model provided by the present invention; Figure 7 A schematic diagram of the decoupling model of the magnetic coupling coil provided by the present invention; Figure 8 A flowchart illustrating an embodiment of the constant voltage and zero phase angle output compensation method provided by the present invention; Figure 9 The present invention provides a curve showing the change of current gain Gvv with frequency under different loads during CV output. Figure 10 The current gain Gvi versus frequency curves under different loads during CC output provided by this invention; Figure 11 The curves showing the input impedance Zinv versus frequency under different loads provided by this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] It should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this invention illustrate operations implemented according to some embodiments of the invention. It should be understood that the operations in the flowcharts may be implemented out of order, and steps without logical contextual relationships may be reversed or performed simultaneously. Furthermore, those skilled in the art, guided by the content of this invention, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor systems and / or microcontroller systems.

[0022] The terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] This invention provides an LCC-S compensation network, a wireless power transmission system, and a compensation method, which are described below.

[0025] Figure 1 A schematic diagram of an embodiment of the LCC-S compensation network provided by the present invention is shown below. Figure 1 As shown, the LCC-S compensation network includes an input port AB, an output port ab, and a compensation circuit; the input port includes a positive input terminal A and a negative input terminal B, and the output port includes a positive output terminal a and a negative output terminal b; The compensation circuit includes a frequency-modulated inductor. Frequency modulation capacitor Primary capacitor Primary equivalent inductance Mutual inductance M, secondary equivalent inductance and secondary capacitor The frequency modulation inductor One end of the frequency modulation inductor is connected to the positive input terminal A. The other end is connected to the frequency modulation capacitor one end and the primary capacitor One end is connected; the frequency modulation capacitor The other end is connected to the negative input terminal B; the primary capacitor The other end is equivalent to the primary side inductance. One end is connected; the primary-side equivalent inductance The other end is connected to one end of the mutual inductance M and one end of the secondary equivalent inductance; the other end of the mutual inductance is connected to the negative output terminal; the secondary equivalent inductance The other end is connected to the secondary capacitor. One end is connected to the secondary capacitor. The other end is connected to the positive output terminal a;

[0026] Wherein, when the input port AB is connected to a constant voltage source or constant current source At that time, by adjusting the frequency modulation inductor Frequency modulation capacitor Primary capacitor and secondary capacitor The value is used to achieve constant voltage and zero phase angle output of the load connected to the output port under the condition that it is independent of the mutual inductance M.

[0027] It should be noted that the primary-side equivalent inductance in the above embodiments... Mutual inductance M, secondary equivalent inductance This is the equivalent circuit structure after decoupling operations; see the appendix for details. Figure 7 In the process, the primary inductance of the magnetically coupled coil is... Secondary inductor The primary-side equivalent inductance is obtained after equivalent processing of the mutual inductance M. Mutual inductance M, secondary equivalent inductance .

[0028] Compared with existing technologies, this invention starts from mathematical calculations and circuit characteristics, constructs an LCC-S compensation network using a matrix model, analyzes the relevant compensation conditions for stable output of coupled resonance in wireless power transmission systems through an assumption method, and achieves constant voltage output independent of mutual inductance by reasonably setting the compensation network and compensation method. Furthermore, this invention provides a general method for calculating the CC output, CV output, ZPA condition, voltage gain Gvv, and current gain Gvi of the compensation network, providing a solid theoretical foundation for subsequent compensation network construction.

[0029] Generally, compensation networks are composed of capacitive and inductive devices. The equivalent series resistance (ESR) of the capacitor is very small, and usually only the ESR of the coil is considered. For specific implementation details, please refer to [link to relevant documentation]. Figure 2 The LCC-S compensation network also includes: primary coil resistance. and secondary coil resistance The primary coil resistance One end is connected to the primary capacitor Connection, the primary coil resistance The other end is equivalent to the primary side inductance. Connection; the secondary coil resistance One end is connected to the secondary capacitor Connection, the primary coil resistance The other end is equivalent to the secondary side inductance. Connection. It should be noted that... Figure 2 Other compensation devices in the process can be Figure 1 frequency modulation inductor Frequency modulation capacitor Primary capacitor and secondary capacitor Other compensation devices can also be used, which will not be elaborated here.

[0030] In some embodiments of the present invention, in the compensation circuit, the circuit components in the LCC-S compensation network can be modified according to the duality of the compensation network to also serve as an LCC-S compensation network that achieves constant voltage and zero phase angle output of the load under conditions independent of mutual inductance.

[0031] For details, please refer to [link / reference]. Figure 3 Based on the duality characteristic, the circuit positions of the frequency modulation inductor and the frequency modulation capacitor are interchanged, that is: the frequency modulation inductor... Replace with and frequency modulation capacitor Replace with .

[0032] Furthermore, in some embodiments of the present invention, please refer to... Figure 4 In the compensation circuit, based on the duality characteristic, the circuit positions of the frequency modulation inductor and the frequency modulation capacitor are adjusted to be between the secondary capacitor and the output port, that is: the frequency modulation inductor... Move it to the output port ab side as a frequency modulation inductor , frequency modulation capacitor Move it to the output port ab side as a frequency modulation capacitor. .

[0033] Furthermore, in some embodiments of the present invention, please refer to... Figure 5 In the compensation circuit, the circuit positions of the frequency modulation inductor and the frequency modulation capacitor located between the secondary capacitor and the output port are swapped, that is: Figure 4 frequency modulation inductor With frequency modulation capacitor The positions were swapped.

[0034] To achieve the above objectives, the present invention also provides a wireless power transmission system; please refer to [link / reference needed]. Figure 1 It includes the LCC-S compensation network as described in the above embodiment, and also includes a constant voltage source. or constant current source and the load; the constant voltage source or constant current source The load is connected to the input port AB and the output port ab.

[0035] Specifically, constant voltage and zero phase angle output of the load are achieved under conditions unrelated to mutual inductance by adjusting the values ​​of the frequency modulation inductor, frequency modulation capacitor, primary capacitor, and secondary capacitor.

[0036] It should be noted that the wireless power transmission system provided in this embodiment of the invention mainly relies on the LCC-S compensation network to achieve constant voltage and zero phase angle output of the load. Its implementation method and function are similar to those of the LCC-S compensation network provided in the above embodiment, and its implementation process will not be described in detail here.

[0037] To achieve the above objectives, the present invention also provides a constant voltage and zero phase angle output compensation method, based on the above-described LCC-S compensation network, or, as described above, a wireless power transmission system.

[0038] Please see Figure 8 The compensation method includes: Step S801: Construct an equivalent model of the basic transmission matrix based on the reciprocal two-port network, and determine the zeroing condition of the matrix coefficients in the equivalent model of the basic transmission matrix under the condition of constant voltage input or constant current input and constant voltage and zero phase angle output, which is independent of mutual inductance. Step S802: Based on the basic transmission matrix equivalent model, a model is created for the LCC-S compensation network to obtain the LCC-S compensation network transmission matrix equivalent model. After setting the matrix coefficients of the LCC-S compensation network transmission matrix equivalent model to zero according to the zeroing situation of the matrix coefficients in the basic transmission matrix equivalent model, the relationship between the frequency modulation inductor, frequency modulation capacitor, primary side capacitor, secondary side capacitor and tuning frequency is obtained. Step S803: Determine the resonance condition based on the relationship between the frequency modulation inductor, frequency modulation capacitor, primary side capacitor, secondary side capacitor and tuning frequency. Step S804: Substitute the matrix coefficients corresponding to the resonance condition into the equivalent model of the LCC-S compensation network transmission matrix to obtain the target LCC-S compensation network, and perform constant voltage and zero phase angle output compensation based on the target LCC-S compensation network.

[0039] In some embodiments of the present invention, determining the zeroing condition of the matrix coefficients in the equivalent model of the basic transmission matrix under constant voltage input or constant current input and constant voltage and zero phase angle output conditions independent of mutual inductance includes: When the input voltage is constant, if it is necessary to keep it independent of mutual inductance, the matrix coefficients related to the mutual inductance value are set to zero. If it is necessary to keep the output voltage constant, the matrix coefficients related to the output current in the voltage source expression are set to zero. If it is necessary to keep the output voltage zero, the matrix coefficients related to the output voltage in the current source expression are set to zero. When a constant current is input, if it is necessary to maintain independence from mutual inductance, the matrix coefficients related to the mutual inductance value are set to zero. If it is necessary to maintain a constant voltage output, the matrix coefficients related to the output current in the current source expression are set to zero. If it is necessary to maintain a zero phase angle output, the matrix coefficients related to the output voltage in the voltage source expression are set to zero.

[0040] In some embodiments of the present invention, after zeroing the matrix coefficients of the equivalent model of the LCC-S compensation network transmission matrix according to the zeroing status of the matrix coefficients in the equivalent model of the basic transmission matrix, the relationship between the frequency-modulated inductor, frequency-modulated capacitor, primary-side capacitor, secondary-side capacitor, and tuning frequency is obtained, including: When a constant voltage input is applied, the matrix coefficients related to the mutual inductance value are set to zero to obtain the relationship between the frequency-modulated inductor, frequency-modulated capacitor, and tuning frequency. The matrix coefficients related to the output current in the voltage source expression are set to zero to obtain the relationship between the frequency-modulated inductor, frequency-modulated capacitor, primary-side capacitor, secondary-side capacitor, and tuning frequency. The matrix coefficients related to the output voltage in the current source expression are set to zero to obtain the relationship between the frequency-modulated inductor, frequency-modulated capacitor, primary-side capacitor, and tuning frequency.

[0041] In some embodiments of the present invention, the method further includes: Determine the input-output gain and input impedance when the input is constant voltage or constant current and the output is constant voltage and zero phase angle under conditions independent of mutual inductance; Determine the input apparent power and input-output efficiency when the input is constant voltage or constant current and the output is constant voltage and zero phase angle under conditions independent of mutual inductance.

[0042] To further explain in detail how the compensation method of this invention compensates for constant voltage and zero phase angle outputs, please refer to [the relevant documentation / reference needed]. Figures 1-11 .

[0043] In step S801, an equivalent model of the basic transmission matrix is ​​constructed based on the reciprocal two-port network as follows: Figure 6 The transmission matrix is ​​analyzed using a T-matrix, specifically using superscript bands. To represent a vector, the input voltage is represented by U. AB Or U1, the output voltage is represented by U. ab Or, if U2 represents it, then:

[0044]

[0045] in, , , and These are the matrix coefficients.

[0046] If written as a matrix equation as follows:

[0047] Therefore, the expressions for the output voltage and output current can be derived as follows:

[0048] In this embodiment, a purely resistive load is used, so the output voltage U2 and the output current I2 are in phase, that is:

[0049] In the above formula, the superscript "*" indicates a conjugate complex number, and R represents the load resistance.

[0050] It can be proven by mathematical induction that in a compensation network containing only inductors and capacitors, the T matrix contains... , For pure real numbers, , It is a purely imaginary number and a reciprocal two-port network, satisfying... The relational formula. It should be noted that obtaining the above conclusion through mathematical induction is achievable with current technology, and will not be elaborated upon here.

[0051] To determine the zeroing of matrix coefficients in the equivalent model of the basic transmission matrix in step S801 when there is constant voltage or constant current input and the output is maintained at constant voltage and zero phase angle without mutual inductance, the following four cases need to be analyzed: To achieve a CC output with a voltage source input, then ,at this time At this point, the output current depends only on the input voltage. The zero-phase angle ZPA condition for CC output is... ,at this time ,Right now:

[0052]

[0053] in, This represents the input voltage, output current, and gain. This indicates the input impedance.

[0054] To achieve CV output with a voltage source input, then ,at this time At this point, the output voltage depends only on the input voltage. The ZPA condition for CV output is... , at this time ,Right now:

[0055]

[0056] To achieve a CC output for a current source input, then ,at this time At this point, the output current depends only on the input current. The ZPA condition for CC output is... ,at this time ,Right now:

[0057]

[0058] To achieve CV output with a current source input, then At this point, the output voltage depends only on the input current. The ZPA condition for CC output is... ,at this time ,Right now:

[0059]

[0060] It should be noted that the above discussion covered the output characteristics of the CC / CV circuit and the corresponding expressions for gain and input impedance under constant voltage and constant current input conditions. It's important to point out that satisfying the CC / CV characteristics alone is of practical significance, but satisfying the ZPA condition alone has no physical meaning. This method simplifies the difficulty of determining the CC / CV resonance condition.

[0061] To further understand the circuit characteristics of the equivalent model of the LCC-S compensation network transmission matrix, the input apparent power and output efficiency are calculated as follows: The input apparent power can be calculated from the above formula as follows:

[0062] In the above formula, Re represents the real part of the complex number, and Im represents the imaginary part of the complex number. Therefore, the output efficiency expression is: .

[0063] To further determine the equivalent model of the LCC-S compensation network transmission matrix obtained by creating the model of the LCC-S compensation network based on the equivalent model of the basic transmission matrix in step S802, the matrix coefficients of the equivalent model of the LCC-S compensation network transmission matrix are correspondingly zeroed according to the zeroing of the matrix coefficients in the equivalent model of the basic transmission matrix. After obtaining the relationship between the frequency modulation inductor, frequency modulation capacitor, primary side capacitor, secondary side capacitor and tuning frequency, the matrix coefficients need to be calculated and analyzed.

[0064] Specifically, in wireless power transmission, the coupling coefficient k or mutual inductance M is usually used to represent the degree of coupling, and the relationship between the two is as follows: .

[0065] In WPTS, k typically takes a value between 0.1 and 0.4, and is also known as a loosely coupled system.

[0066] The equivalent model of the LCC-S compensated network transmission matrix is ​​attached. Figure 1 Given the given information, write out the cascaded network of matrix T:

[0067] It should be noted here that in this T-matrix cascaded network , , and The matrix coefficients in the equivalent model of the LCC-S compensation network transmission matrix are compared with those in the equivalent model of the basic transmission matrix mentioned above. , , and The essence is the same, but they describe two different local matrix parameters. Those skilled in the art can understand the difference in their descriptions through the content of the specification.

[0068] Specifically, ~ They are respectively:

[0069]

[0070]

[0071]

[0072]

[0073] It should be noted that, ~ It is Figure 1 Medium frequency modulation inductor Frequency modulation capacitor Primary capacitor Secondary capacitor , Figure 7 Primary inductance in Secondary inductor And mutual inductance M, and tuning frequency Substitute the value into Figure 6 The conversion process is calculated in the equivalent model of the basic transmission matrix. It is obtained through matrix calculation, which can be deduced by those skilled in the art based on mathematical common sense. The process will not be described in detail here.

[0074] Furthermore, to achieve the resonance condition of CV & ZPA output independent of M, the following equation should be satisfied: .

[0075] Understandably, in order to achieve independence from M, it is necessary to... To achieve constant voltage output (CV), the expression associated with M is set to zero. To achieve CV&ZPA output, set it to zero. Set to zero.

[0076] The T matrix at this point can be written as follows:

[0077] At this point, the input voltage, output voltage gain, and input impedance can be written as: .

[0078] Furthermore, the resonance conditions under CV & ZPA are:

[0079] The T network incorporated into LCC-S includes: .

[0080] After the above steps, the matrix coefficients under resonance conditions in the equivalent model of the LCC-S compensation network transmission matrix can be calculated. Then, the frequency modulation inductor, frequency modulation capacitor, primary side capacitor, secondary side capacitor, and tuning frequency can be adjusted and set according to these matrix coefficients.

[0081] The following section explains how to achieve resonance conditions independent of M from a circuit perspective, as shown in the attached diagram. Figure 7 As shown, the T matrix of the primary and secondary coupled coils is written as follows:

[0082] Clearly, if the compensation network can compensate for L1 and L2, then the matrix can be written as:

[0083] From the TM matrix, we can see that a constant current output independent of M can be achieved with a constant voltage source input (or a ZPA condition under a constant current source input and a CV output independent of M). LCC-S can only be regarded as two cascaded T networks, thus it can achieve a CV & ZPA output independent of the resonance condition and the mutual inductance M (or coupling coefficient).

[0084] Furthermore, considering that the compensation network consists of capacitive and inductive devices, and the equivalent series resistance (ESR) of the capacitor is very small, usually only the ESR of the coil is considered. Let the equivalent series resistance of the primary side be Rp, and the equivalent series resistance of the secondary side be Rs, as shown in the attached diagram. Figure 2 As shown, the T matrix at constant voltage output is written as follows:

[0085] Therefore, its efficiency can be calculated as follows:

[0086] Taking the partial derivative with respect to M, we have:

[0087] The above equation shows that although the resonance condition is independent of mutual inductance during constant voltage output, the efficiency increases with the increase of mutual inductance. To maintain high efficiency during constant voltage output, M needs to be large.

[0088] To verify how the above compensation method can achieve constant voltage and zero phase angle output compensation, please refer to [link / reference needed]. Figures 9-11 ,in, Figure 9 The present invention provides a curve showing the change of current gain Gvv with frequency under different loads during CV output. Figure 10 The current gain Gvi versus frequency curves under different loads during CC output provided by this invention; Figure 11 The graph shows the input impedance Zinv versus frequency under different loads, as provided by this invention. Specifically, from... Figure 9 It can be seen that the voltage gain is 1.5035 at a frequency of 90kHz (resonant frequency); Figure 10 As can be seen, the voltage gain is 0.316 at a frequency of 80kHz; Figure 11 It can be seen from this that... or ZPA can be achieved at this time.

[0089] It should be noted that, Figures 9-11 The parameters of the magnetic coupling system used are shown in Table 1 below: Table 1: Parameters of the magnetic coupling system

[0090] Furthermore, the input-output characteristics of the LCC-S dual network ( Figures 3-5 The study was conducted, as shown in Table 2. Table 2: Input and Output Characteristic Parameters of LCC-S Dual Network

[0091] Table 2 presents the dual topological resonance condition and the efficiency expressions for Gvv, Zinv and CV output. The table shows that the parameters of each device can be calculated and substituted into the table under the CV resonance condition. It can also be seen from the expressions that the CV resonance condition is independent of M.

[0092] In summary, the LCC-S compensation network, wireless power transmission system, and compensation method provided by this invention, starting from mathematical calculations and circuit characteristics, construct the LCC-S compensation network using a matrix model. It analyzes the relevant compensation conditions for stable coupled resonance output in the wireless power transmission system using an assumption method, and achieves constant voltage output independent of mutual inductance by rationally setting the compensation network and compensation method. Furthermore, this invention provides a general method for calculating the CC output, CV output, ZPA condition, voltage gain Gvv, and current gain Gvi of the compensation network, providing a solid theoretical foundation for subsequent compensation network construction.

[0093] The LCC-S compensation network, wireless power transmission system, and compensation method provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A constant voltage and zero phase angle output compensation method, applied to an LCC-S compensation network, characterized in that, The LCC-S compensation network includes: an input port, an output port, and a compensation circuit; the input port includes a positive input terminal and a negative input terminal, and the output port includes a positive output terminal and a negative output terminal; The compensation circuit includes a frequency-modulated inductor, a frequency-modulated capacitor, a primary capacitor, a primary equivalent inductance, a mutual inductance, a secondary equivalent inductance, and a secondary capacitor. One end of the frequency-modulated inductor is connected to the positive input terminal, and the other end of the frequency-modulated inductor is connected to one end of the frequency-modulated capacitor and one end of the primary capacitor. The other end of the frequency-modulated capacitor is connected to the negative input terminal. The other end of the primary capacitor is connected to one end of the primary equivalent inductance. The other end of the primary equivalent inductance is connected to one end of the mutual inductance and the secondary equivalent inductance. One end of the mutual inductance is connected; the other end of the mutual inductance is connected to the negative output terminal; the other end of the secondary equivalent inductance is connected to one end of the secondary capacitor, and the other end of the secondary capacitor is connected to the positive output terminal; primary coil resistor and secondary coil resistor; one end of the primary coil resistor is connected to the primary capacitor, and the other end of the secondary coil resistor is connected to the primary equivalent inductance; one end of the secondary coil resistor is connected to the secondary capacitor, and the other end of the primary coil resistor is connected to the secondary equivalent inductance; When the input port is connected to a constant voltage source or a constant current source, the constant voltage and zero phase angle output of the load connected to the output port can be achieved by adjusting the values ​​of the frequency modulation inductor, frequency modulation capacitor, primary capacitor and secondary capacitor, without being related to mutual inductance. The compensation method includes: A basic transmission matrix equivalent model is constructed based on a reciprocal two-port network, and the zeroing of matrix coefficients in the basic transmission matrix equivalent model is determined under the condition of constant voltage input or constant current input and constant voltage and zero phase angle output, which is independent of mutual inductance. Based on the basic transmission matrix equivalent model, the LCC-S compensation network is modeled to obtain the LCC-S compensation network transmission matrix equivalent model. After setting the matrix coefficients of the LCC-S compensation network transmission matrix equivalent model to zero according to the zeroing situation of the matrix coefficients in the basic transmission matrix equivalent model, the relationship between the frequency modulation inductor, frequency modulation capacitor, primary side capacitor, secondary side capacitor and tuning frequency is obtained. The resonance condition is determined based on the relationship between the frequency-modulated inductor, frequency-modulated capacitor, primary-side capacitor, secondary-side capacitor, and tuning frequency. Substitute the matrix coefficients corresponding to the resonance condition into the equivalent model of the LCC-S compensation network transmission matrix to obtain the target LCC-S compensation network, and perform constant voltage and zero phase angle output compensation based on the target LCC-S compensation network.

2. The constant voltage and zero phase angle output compensation method according to claim 1, characterized in that, In the compensation circuit, the circuit positions of the frequency modulation inductor and the frequency modulation capacitor are swapped.

3. The constant voltage and zero phase angle output compensation method according to claim 1, characterized in that, In the compensation circuit, the circuit positions of the frequency modulation inductor and frequency modulation capacitor are adjusted to be between the secondary capacitor and the output port.

4. The constant voltage and zero phase angle output compensation method according to claim 3, characterized in that, In the compensation circuit, the circuit positions of the frequency modulation inductor and the frequency modulation capacitor located between the secondary capacitor and the output port are swapped.

5. The constant voltage and zero phase angle output compensation method according to claim 1, characterized in that, Determining the zeroing conditions of the matrix coefficients in the equivalent model of the basic transmission matrix under constant voltage or constant current input conditions and constant voltage and zero phase angle output conditions independent of mutual inductance includes: When the input voltage is constant, if it is necessary to keep it independent of mutual inductance, the matrix coefficients related to the mutual inductance value are set to zero. If it is necessary to keep the output voltage constant, the matrix coefficients related to the output current in the voltage source expression are set to zero. If it is necessary to keep the output voltage zero, the matrix coefficients related to the output voltage in the current source expression are set to zero. When a constant current is input, if it is necessary to maintain independence from mutual inductance, the matrix coefficients related to the mutual inductance value are set to zero. If it is necessary to maintain a constant voltage output, the matrix coefficients related to the output current in the current source expression are set to zero. If it is necessary to maintain a zero phase angle output, the matrix coefficients related to the output voltage in the voltage source expression are set to zero.

6. The constant voltage and zero phase angle output compensation method according to claim 5, characterized in that, After zeroing the matrix coefficients of the LCC-S compensated network transmission matrix equivalent model according to the zeroing condition of the matrix coefficients in the basic transmission matrix equivalent model, the relationship between the frequency modulation inductor, frequency modulation capacitor, primary-side capacitor, secondary-side capacitor, and tuning frequency is obtained, including: When a constant voltage input is applied, the matrix coefficients related to the mutual inductance value are set to zero to obtain the relationship between the frequency-modulated inductor, frequency-modulated capacitor, and tuning frequency. The matrix coefficients related to the output current in the voltage source expression are set to zero to obtain the relationship between the frequency-modulated inductor, frequency-modulated capacitor, primary-side capacitor, secondary-side capacitor, and tuning frequency. The matrix coefficients related to the output voltage in the current source expression are set to zero to obtain the relationship between the frequency-modulated inductor, frequency-modulated capacitor, primary-side capacitor, and tuning frequency.

7. The constant voltage and zero phase angle output compensation method according to claim 1, characterized in that, Also includes: Determine the input-output gain and input impedance when the input is constant voltage or constant current and the output is constant voltage and zero phase angle under conditions independent of mutual inductance; Determine the input apparent power and input-output efficiency when the input is constant voltage or constant current and the output is constant voltage and zero phase angle under conditions independent of mutual inductance.

8. A wireless power transmission system, characterized in that, Includes an LCC-S compensation network for implementing the constant voltage and zero phase angle output compensation method as described in any one of claims 1-7; The system also includes a constant current source or a constant voltage source, and a load; the constant current source or constant voltage source is connected to the input port, and the load is connected to the output port; Specifically, constant voltage and zero phase angle output of the load are achieved under conditions unrelated to mutual inductance by adjusting the values ​​of the frequency modulation inductor, frequency modulation capacitor, primary capacitor, and secondary capacitor.

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