WO2023217054A1

WO2023217054A1 - Voltage optimization joint control method for use in multi-module wireless charging system

Info

Publication number: WO2023217054A1
Application number: PCT/CN2023/092629
Authority: WO
Inventors: 钟文兴; 徐德鸿; 朱晨
Original assignee: 浙江大学
Priority date: 2022-05-07
Filing date: 2023-05-07
Publication date: 2023-11-16
Also published as: CN114726111A

Abstract

A voltage optimization joint control method for use in a multi-module wireless charging system is disclosed. The multi-module wireless charging system comprises a plurality of wireless charging modules, and each wireless charging module comprises a transmitting coil, a receiving coil, a transmitting end circuit and a receiving end circuit; the output sides of all the wireless charging modules are connected in parallel, such that said modules output a same load; each of the wireless charging modules uses an LCC compensation topology, the total output current of the multi-module wireless charging system is used as a feedback quantity, the reference input voltage of the multi-module wireless charging system is controlled, and the input voltage amplitude of each wireless charging module is adjusted on the basis of an input voltage amplitude ratio matrix, thus achieving output control and current equalization in the multi-module wireless charging system. The present invention has good universal applicability.

Description

A voltage optimization joint control method suitable for multi-module wireless charging systems

Technical field

The present invention relates to the technical field of wireless power transmission, and in particular to a voltage optimization joint control method suitable for multi-module wireless charging systems.

Background technique

As energy shortages and environmental pollution problems become increasingly serious worldwide, the importance of developing electric vehicles has become increasingly prominent. Wireless charging technology for electric vehicles has attracted much attention due to its advantages such as high efficiency and convenience, low maintenance costs, and no environmental impact. Although low- and medium-power wireless charging technology has achieved certain development, high-power wireless fast charging is still under research. Modular wireless energy transmission technology is helpful in breaking through the power limitations of traditional single-channel wireless charging. However, due to the complex cross-coupling between different modules, the monotonic relationship between the input and output of each module is destroyed, making it difficult to control one of them individually. The output of the module is controlled, so there is no practical application yet.

Contents of the invention

The object of the present invention is to provide a voltage optimization joint control method suitable for a multi-module wireless charging system. The invention can realize current output control and balance of current in each circuit of a multi-module wireless charging system under facing and offset conditions, and has good versatility.

The technical solution of the present invention: a voltage optimization joint control method suitable for a multi-module wireless charging system. The multi-module wireless charging system contains several wireless charging modules. Each wireless charging module includes a transmitting coil, a receiving coil, and a transmitter circuit. and the receiving end circuit; the output sides of all wireless charging modules are connected in parallel to output to the same load; the wireless charging modules The charging modules all adopt LCC compensation topology. The total output current of the multi-module wireless charging system is used as the feedback quantity to control the reference voltage value of the multi-module wireless charging system. The input voltage of each wireless charging module is calculated according to the input voltage amplitude ratio matrix. The amplitude is adjusted, combined with the input voltage phase difference, to achieve output control and current balancing of the multi-module wireless charging system.

The above-mentioned voltage optimization joint control method suitable for multi-module wireless charging systems uses a phase-shifting control method to compare the total output current of the multi-module wireless charging system as a feedback quantity with the total output current reference value, and determines the input voltage through the PID compensation network Reference value, adjust the reference voltage value based on the input voltage reference value.

In the aforementioned voltage optimization joint control method suitable for multi-module wireless charging systems, the determination of the input voltage amplitude ratio matrix includes the following steps: In the first step, first determine the multiple The voltage phase in the module wireless charging system that meets the above conditions is then used to uniquely determine the input voltage phase difference between each wireless charging module through integer programming based on the conditions of optimal efficiency and active power balance on the input side of each wireless charging module; the second step , after determining the input voltage phase, according to the equal current amplitudes of the inverter loop and rectifier bridge loop in the multi-module wireless charging system, the input voltage amplitude ratio matrix of the two wireless charging modules is obtained. For the two input voltage amplitude ratios The matrix is weighted to determine the final input voltage amplitude ratio matrix of the multi-module wireless charging system.

The aforementioned voltage optimization joint control method is suitable for a multi-module wireless charging system. The optimal voltage phase of the multi-module wireless charging system is 0° or 180°.

According to the aforementioned voltage optimization joint control method suitable for multi-module wireless charging systems, the formula for adjusting the input voltage amplitude of each wireless charging module by the input voltage amplitude ratio matrix is as follows:

In the formula: U _inn is the input voltage amplitude of the n-th wireless charging module, n=1,2,3...; r _n is the input voltage amplitude of the n-th wireless charging module and the first wireless charging module Ratio of input voltage amplitude, n=1,2,3...; w _n1 and w _n2 are weight coefficients respectively, n=1,2,3...; Y _inn and Y _outn are dimensionless coefficient expressions , n=1,2,3..., can be calculated through mutual inductance parameters and equivalent AC load resistance.

Compared with the existing technology, the wireless charging modules of the present invention all adopt LCC compensation topology. By using the total output current of the multi-module wireless charging system as a feedback quantity, the reference voltage value (i.e., the reference phase shift angle) of the multi-module wireless charging system is ) is controlled, and then the input voltage amplitude of each wireless charging module is adjusted according to the input voltage amplitude ratio matrix. Combined with the input voltage phase difference, the output control of any multi-module wireless charging system under direct alignment and offset conditions is realized. And the purpose of basic balancing of each loop current. The method of the present invention can be used to control the total output current of a multi-module wireless charging system with LCC topology and the basic balance of each loop current through control means, and is suitable for various types of multi-module wireless charging systems, and the compensation method, load properties, The number and placement of modules do not affect the versatility of this solution, and it has good adaptability.

Description of the drawings

Figure 1 is a conceptual diagram of a multi-module wireless charging system;

Figure 2 is the equivalent circuit of a two-module wireless charging system with LCC topology;

Figure 3 shows the fundamental wave equivalent circuit of a two-module wireless charging system with LCC topology;

Figure 4 is the voltage optimization joint control block diagram of the multi-module wireless charging system with LCC topology;

Figure 5 is a simulation coil structure diagram of a seven-module wireless charging system with LCC topology;

Figure 6 shows the inverter loop current waveform when the seven-module wireless charging system with LCC topology faces directly;

Figure 7 shows the rectifier bridge loop current waveform when the seven-module wireless charging system with LCC topology is facing directly.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and examples, but this does not serve as a basis for limiting the present invention.

Embodiment: A voltage-optimized joint control method suitable for a multi-module wireless charging system. The multi-module wireless charging system contains several wireless charging modules. Each wireless charging module includes a transmitting coil, a receiving coil and a set of independent The transmitter circuit and the receiver circuit; the transmitter circuit is composed of a DC input, an inverter, and a compensation network with an LCC structure; the receiver circuit is composed of a rectifier bridge and a compensation network with an LCC structure (it can also include a DC-DC converter). And the parameters in the LCC compensation network are consistent with the parameters when the single-channel bilateral LCC structure wireless charging system is fully compensated. The output sides of all wireless charging modules are connected in parallel to output to the same load; the wireless charging modules all adopt LCC compensation topology.

In this embodiment, the multi-module wireless charging system is shown in Figure 1. Taking the two-module system as an example to analyze the input-output relationship of the LCC topology multi-module wireless charging system, the equivalent circuit is shown in Figure 2, the fundamental wave equivalent circuit is shown in Figure 3, and the parameter settings of the LCC compensation circuit are as follows:

Among them: the subscript *(*＝1,2,…,n) represents the *th module; ω ₀ represents the resonant frequency, L _fT* and L _fR* represent the series compensation inductance of the primary and secondary sides respectively, L _T* and L _R* represent the self-inductance of the transmitting coil and the receiving coil respectively, C _fT* and C _fR* represent the parallel compensation capacitance of the primary side and the secondary side respectively; C _T* and C _R* represent the series connection of the primary side and the secondary side respectively. compensation capacitor, and represent the currents of the series compensation inductors on the primary side and secondary side respectively, and represent the currents of the transmitting coil and receiving coil respectively;

According to equation (1) and Figure 3, the current value of each loop is obtained:

Extend the above current expression to an n-module wireless charging system, where the current expression of the i-th module is:

It can be seen from equation (3) that the transmitting coil current of each wireless charging module in the multi-module wireless charging system is only affected by the input voltage amplitude, and the receiving coil current amplitude of each wireless charging module is only affected by the output voltage amplitude. And completely equal. By setting the upper limit of the input voltage amplitude, the maximum current of the transmitting coil can be determined; considering the maximum overshoot of the output voltage amplitude during the closed-loop adjustment process, the maximum current of the receiving coil can be determined. And the above maximum current is not affected by the coil position, current system power, etc. Therefore, the maximum current of the coil can be calculated at the design stage, and this maximum current will not be exceeded under any extreme circumstances. Therefore, the main purpose of multi-module wireless charging system control is to ensure the basic balance of the inverter and rectifier bridge loop currents.

The method adopted in this embodiment is to use the total output current of the multi-module wireless charging system as a feedback quantity, control the reference voltage value (ie, phase shift angle) of the multi-module wireless charging system, and adjust each wireless charging system according to the input voltage amplitude ratio matrix. The input voltage amplitude (ie, phase shift angle) of the charging module is adjusted to achieve output control and current balancing of the multi-module wireless charging system.

Among them, the phase-shift control method is used to compare the total output current of the multi-module wireless charging system as a feedback quantity with the total output current reference value, and the input current is determined through the PID compensation network. Voltage reference value, adjust the reference voltage value according to the input voltage reference value.

The determination of the input voltage secondary value ratio matrix is to first determine the voltage phase of the multi-module wireless charging system, and then calculate the ratio of each wireless charging module through integer programming based on the conditions of optimal efficiency and active power balance on the input side of each wireless charging module. The input voltage phase difference between The input voltage amplitude ratio matrix is weighted to determine the final input voltage amplitude ratio matrix of the multi-module wireless charging system.

The following is still taking a wireless charging system with two wireless charging modules as an example. For a multi-module wireless charging system that is rotationally symmetric about the z-axis, there is a symmetrical relationship between the cross-coupling at the offset position of the spatial symmetry, the positive coupling and the same side coupling. The cross-coupling relationship can be written as follows:

The superscript ' represents the parameter of one of the symmetric offset positions.

For the above-mentioned multi-module wireless charging system, the voltage stress should be minimized in a spatially symmetrical position. Assuming that the current distribution at a symmetric position in space is asymmetric, you can always adjust the amplitude and phase distribution of the input voltage to reduce the amplitude of the loop current with the largest amplitude and find a better solution. This shows that symmetry of current distribution at spatially symmetric positions is a necessary but not sufficient condition for minimizing current stress. Therefore, the partial symmetry of the current at a symmetric position in space is used as a condition to solve the input voltage phase.

Since the transmitting coil current is only affected by the input voltage, the symmetrical relationship of the input voltage can be obtained through the symmetrical relationship of the transmitting coil current. The relationship between input voltage and non-same-side cross-coupling is as follows:

Where U _in* represents the amplitude of the input voltage.

Express the output voltage as the product of the output current and the equivalent AC load resistance and put it into equation (2), we get and

where R _L* represents the equivalent AC load resistance.

According to the condition of current symmetry:

Putting equation (7) into equation (6), we can get

For any input voltage amplitude, equation (7) should be established, and it can be obtained:

θ ₁₂ ＝θ ₂ -θ ₁ ＝0°or 180°, equation (9)

θ ₁ and θ ₂ represent the input voltage phases of the first and second modules respectively, and θ ₁₂ represents the input voltage phase difference between the first module and the second module, which is the maximum limit of the multi-module wireless charging system. The optimal input voltage phase difference is 0° or 180°.

Substituting the phase of equation (9) back into equation (2), we can derive and The amplitudes are equal. Based on the two conditions that the active power is transferred from the primary side to the secondary side as much as possible and the active power on the primary side of each module is balanced as much as possible, the following integer programming equation can be written:

in

For greater clarity, the above equation uses a four-module wireless charging system as an example. The above formula can be simply explained as trying to reverse the input voltage of adjacent modules while ensuring the balance of active power on the primary side.

Expressing the output voltage as the product of the output current and the equivalent AC load resistance and bringing it into equation (3), the following matrix equations can be simplified:

In the formula: Y _{inn_n} and Y _{outn_n} are the admittance coefficients respectively, n=1,2,3..., the admittance coefficient Y _{inn_n} and the admittance coefficient Y _{outn_n} are calculated through the mutual inductance parameters and the equivalent AC load resistance; where the mutual inductance The parameters can be obtained through offline measurement, and the equivalent AC load resistance can be calculated based on the output resistance and output side current.

Put the phase obtained by equation (9) into equation (12), and according to the current symmetry condition, we can get:

In the formula, Y _inn is the expression of the dimensionless coefficient Y _{inn_n} , and Y _outn is the expression of the dimensionless coefficient Y _{outn_n} ;

Through the asymmetry of the inverter loop current and the rectifier bridge loop current, determine the weight coefficients w _1n and w _2n , n=1,2,3...; and perform weighting processing to obtain:

In the formula: U _inn is the input voltage amplitude of the nth wireless charging module, n = 1, 2, 3...; r _n is the input voltage amplitude of the nth wireless charging module and the first wireless charging The ratio of module input voltage amplitude, n=1,2,3...; w _n1 and w _n2 are weight coefficients respectively, n=1,2,3...; Y _inn and Y _outn are dimensionless coefficients The expression, n=1,2,3..., can be calculated from the mutual inductance parameters and the equivalent AC load resistance.

According to the relationship between fundamental wave input voltage and phase shift angle:

The input voltage amplitude and the input phase shift angle can be converted into each other. In order to ensure consistency in expression, the control variable is selected as the input voltage amplitude.

At this time, the phase and amplitude ratio of the input voltage have been determined, and the control block diagram of the multi-module wireless charging system can be obtained, as shown in Figure 4 (phase shift modulation in Figure 4 is the control method of phase shift modulation; gate driver signal of module is the driving signal of the wireless charging module). In this way, the input voltage amplitude (i.e., phase shift angle) of each wireless charging module is adjusted according to the input voltage amplitude ratio matrix to achieve current output control and each loop current of the multi-module wireless charging system under direct alignment and offset conditions. of equilibrium.

This embodiment takes a seven-module wireless charging system with a rated power of 200KW as an example, and performs verification in two situations: facing directly and offset by 7.5cm. The coil structure uses hexagonal coils, and the spatial structure is shown in Figure 5. The simulation can obtain the inductance and phase parameters as shown in Table 1 Shown:

Table 1

The electrical parameters in the circuit simulation are shown in Table 2:

Table 2

The circuit structure, compensation method and transmitter inverter control method are all set according to the embodiment of the present invention. The circuit simulation waveform diagram obtained by using the method of the present invention is shown in Figure 6 and Figure 7. Compare this control method with the joint control method using the voltage phases in Table 1 and the joint control method in which the input voltages are all in the same direction. The comparison results in the case of direct alignment and offset are shown in Table 3 and Table 4 below respectively:

Table 3 Comparison of simulation results (face to face)

Table 4 Comparison of simulation results (offset)

It can be seen from the circuit simulation comparison results in Table 3 and Table 4 that the output control of the present invention under the direct alignment and offset conditions of the multi-module wireless charging system is better than the current balance when only joint control is used. The degree is smaller and more suitable for multi-module wireless charging systems.

To sum up, the wireless charging modules of the present invention all adopt LCC compensation topology. By using the total output current of the multi-module wireless charging system as a feedback quantity, the reference input voltage of the multi-module wireless charging system is controlled, and then the reference input voltage of the multi-module wireless charging system is controlled according to the input voltage amplitude. The value ratio matrix adjusts the input voltage of each wireless charging module, achieving the purpose of output control of any multi-module wireless charging system under direct alignment and offset conditions and the basic balancing of each loop current. The method of the present invention can be used to control the total output current of a multi-module wireless charging system with LCC topology and the basic balance of each loop current through control means, and is suitable for various types of multi-module wireless charging systems, and the compensation method, load properties, The number and placement of modules do not affect the versatility of this solution, and it has good adaptability.

Claims

A voltage-optimized joint control method suitable for a multi-module wireless charging system. The multi-module wireless charging system contains several wireless charging modules. Each wireless charging module includes a transmitting coil, a receiving coil, a transmitting end circuit and a receiving end circuit; all The output sides of the wireless charging modules are connected in parallel to output to the same load; it is characterized in that: the wireless charging modules all adopt LCC compensation topology, and the total output current of the multi-module wireless charging system is used as the feedback amount, and the multi-module wireless charging system is The reference voltage value is controlled, and the input voltage amplitude of each wireless charging module is adjusted according to the input voltage amplitude ratio matrix. Combined with the input voltage phase difference, the output control and current balance of the multi-module wireless charging system are achieved.
The voltage optimization joint control method suitable for multi-module wireless charging systems according to claim 1, characterized in that: a phase-shifting control method is used to control the total output current of the multi-module wireless charging system as a feedback amount and a total output current reference value. Compare, determine the input voltage reference value through the PID compensation network, and adjust the reference voltage value based on the input voltage reference value.
The voltage optimization joint control method suitable for multi-module wireless charging systems according to claim 1, characterized in that: determining the input voltage amplitude ratio matrix includes the following steps: the first step, first passing through each loop at a spatially symmetrical position Under the condition that the current amplitudes are equal, determine the voltage phase that meets the above conditions in the multi-module wireless charging system, and then determine the voltage phase between each wireless charging module through integer programming based on the conditions of optimal efficiency and active power balance on the input side of each wireless charging module. Input voltage phase difference; in the second step, after determining the input voltage phase, according to the equal current amplitudes of the inverter loop and rectifier bridge loop in the multi-module wireless charging system, the input voltage amplitude ratio matrix of the two wireless charging modules is obtained, For two input power The voltage amplitude ratio matrix is weighted to determine the final input voltage amplitude ratio matrix of the multi-module wireless charging system.
The voltage optimization joint control method suitable for a multi-module wireless charging system according to claim 3, characterized in that: the optimal voltage phase of the multi-module wireless charging system is 0° or 180°.
The voltage optimization joint control method suitable for multi-module wireless charging systems according to claim 3, characterized in that: the formula for adjusting the input voltage amplitude of each wireless charging module by the input voltage amplitude ratio matrix is as follows:

In the formula: U inn is the input voltage amplitude of the n-th wireless charging module, n=1,2,3...; r n is the input voltage amplitude of the n-th wireless charging module and the first wireless charging module Ratio of input voltage amplitude, n=1,2,3...; w n1 and w n2 are weight coefficients respectively, n=1,2,3...; Y inn and Y outn are dimensionless coefficient expressions , n=1,2,3..., calculated through mutual inductance parameters and equivalent AC load resistance.