Phase synchronization method, system, readable storage medium and computer

Abstract

The present invention provides a phase synchronization method, system, readable storage medium and computer, the method comprising: initializing the transmission direction of a dual LCLC compensated bidirectional EC-WPT system, and controlling the primary and secondary converters to perform fixed frequency operation at their corresponding initial operating frequencies respectively; after a preset working cycle, performing zero-crossing sampling on the primary converter and the secondary converter to obtain square wave synchronous voltage signals of the primary converter and the secondary converter; generating a driving signal of the dual LCLC compensated bidirectional EC-WPT system according to the transmission direction and the square wave synchronous voltage signals of the primary converter and the secondary converter, and self-excitedly driving the converter by following the zero-crossing point of the resonant current, and finally operating at a stable resonant frequency, thereby achieving accurate phase synchronization. The phase synchronization method proposed by the present invention is still applicable when the coupling capacitance changes.

Description

Technical Field

[0001] The present invention relates to the field of wireless power transmission technology, and in particular to a phase synchronization method, system, readable storage medium and computer. Background Art

[0002] At present, the research on bidirectional EC-WPT technology is in its infancy. The current achievements are mainly based on the analysis and research of the phase-shifted power flow control method of the bidirectional EC-WPT system based on the typical bilateral symmetrical full-bridge conversion topology. The amplitude and direction of the system transmission power can be adjusted by the amplitude and relative phase difference of the output voltage of the primary and secondary converters. However, in engineering practice, since the primary and secondary sides of the bilateral physically isolated bidirectional EC-WPT system usually use two independent controllers, the phase asynchrony of the output voltage of the primary and secondary converters of the system will cause problems such as periodic changes in the relative phase difference and continuous power oscillation.

[0003] In addition, since the bidirectional EC-WPT system generally uses frequencies of MHz and above to reduce the size and volume of the compensation inductor, the accuracy of phase synchronization needs to be controlled within a high-frequency environment. μ Although traditional wireless communication technology can obtain the phase information of the primary and secondary sides, it has a large delay and is susceptible to electromagnetic interference, which affects the accuracy and stability of the phase synchronization control of the bidirectional EC-WPT system. Summary of the invention

[0004] Based on this, an object of the present invention is to provide a phase synchronization method, system, readable storage medium and computer to at least solve the deficiencies in the above-mentioned technology.

[0005] The present invention proposes a phase synchronization method, which is applicable to a dual LCLC compensation bidirectional EC-WPT system with a changing coupling capacitance, and the method comprises:

[0006] Initializing the transmission direction of the dual LCLC compensated bidirectional EC-WPT system, and controlling the primary and secondary side converters to perform fixed frequency operation at their corresponding initial operating frequencies respectively;

[0007] After a preset working cycle, the primary converter and the secondary converter are subjected to zero-crossing sampling to obtain square wave synchronous voltage signals of the primary converter and the secondary converter;

[0008] The driving signal of the dual LCLC compensated bidirectional EC-WPT system is generated according to the transmission direction and the square wave synchronous voltage signals of the primary converter and the secondary converter, and the converter is self-excited and driven by following the zero-crossing point of the resonant current, and finally operates at a stable resonant frequency, thereby achieving precise phase synchronization.

[0009] Further, before the step of initializing the transmission direction of the dual LCLC compensation bidirectional EC-WPT system, the method further includes:

[0010] Acquire a system state vector and a system input vector of the dual LCLC compensated bidirectional EC-WPT system, and construct a state space model of the system according to the system state vector and the system input vector;

[0011] The steady-state operation cycle and the working duration of the dual LCLC compensated bidirectional EC-WPT system are obtained, and the periodic fixed point of the dual LCLC compensated bidirectional EC-WPT system is calculated according to the steady-state operation cycle and the working duration, and the corresponding soft switching operating point and the corresponding resonant frequency are analyzed based on the steady-state operation cycle and the periodic fixed point.

[0012] Further, the step of generating a driving signal of the dual LCLC compensated bidirectional EC-WPT system according to the transmission direction and the square wave synchronous voltage signals of the primary converter and the secondary converter includes:

[0013] When the transmission direction is forward power transmission, the primary converter is defined as an inverter, the secondary converter is defined as a synchronous rectifier, the resonant current of the primary converter and the secondary converter is sampled, and the sampled resonant current is compared for zero crossing to output a corresponding square wave synchronous voltage signal;

[0014] The square wave synchronous voltage signal is used to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system to achieve phase synchronization.

[0015] Further, the step of generating a driving signal of the dual LCLC compensated bidirectional EC-WPT system according to the transmission direction and the square wave synchronous voltage signals of the primary converter and the secondary converter includes:

[0016] When the transmission direction is reverse power transmission, the secondary converter is defined as an inverter, the primary converter is defined as a synchronous rectifier, the resonant current of the primary converter and the secondary converter is sampled, and the sampled resonant current is compared for zero crossing to output a corresponding square wave synchronous voltage signal;

[0017] The square wave synchronous voltage signal is used to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system to achieve phase synchronization.

[0018] The present application also proposes a phase synchronization system, which is applied to a dual LCLC compensation bidirectional EC-WPT system with coupling capacitance variation, and the phase synchronization system includes:

[0019] A data initialization module, used to initialize the transmission direction of the dual LCLC compensated bidirectional EC-WPT system, and control the primary and secondary side converters to perform fixed frequency operation at their corresponding initial operating frequencies;

[0020] A zero-crossing sampling module, used for performing zero-crossing sampling on the primary converter and the secondary converter after a preset working cycle, so as to obtain square wave synchronous voltage signals of the primary converter and the secondary converter;

[0021] The phase synchronization module is used to generate a driving signal for the dual LCLC compensated bidirectional EC-WPT system according to the transmission direction and the square wave synchronous voltage signals of the primary converter and the secondary converter, and to self-excite the drive converter by following the zero-crossing point of the resonant current, and finally operate at a stable resonant frequency, thereby achieving precise phase synchronization.

[0022] Furthermore, the system also includes:

[0023] A vector acquisition module, used to acquire a system state vector and a system input vector of the dual LCLC compensated bidirectional EC-WPT system, and construct a state space model of the system according to the system state vector and the system input vector;

[0024] A data calculation module is used to obtain the steady-state operation cycle and working duration of the dual LCLC compensated bidirectional EC-WPT system, and calculate the periodic fixed point of the dual LCLC compensated bidirectional EC-WPT system according to the steady-state operation cycle and the working duration, and analyze the corresponding switch operating point and the corresponding resonant frequency based on the steady-state operation cycle and the periodic fixed point.

[0025] Furthermore, the phase synchronization module includes:

[0026] A forward power transmission unit, used for, when the transmission direction is forward power transmission, defining the primary converter as an inverter and the secondary converter as a synchronous rectifier, sampling the resonant current of the primary converter and the secondary converter, and performing a zero-crossing comparison on the sampled resonant current to output a corresponding square wave synchronous voltage signal;

[0027] The first phase synchronization unit is used to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system using the square wave synchronization voltage signal to achieve phase synchronization.

[0028] Furthermore, the phase synchronization module includes:

[0029] A reverse power transmission unit, used for, when the transmission direction is reverse power transmission, defining the secondary converter as an inverter, defining the primary converter as a synchronous rectifier, sampling the resonant current of the primary converter and the secondary converter, and performing a zero-crossing comparison on the sampled resonant current to output a corresponding square wave synchronous voltage signal;

[0030] The second phase synchronization unit is used to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system using the square wave synchronization voltage signal to achieve phase synchronization.

[0031] The present invention also provides a readable storage medium on which a computer program is stored, and when the program is executed by a processor, the above-mentioned phase synchronization method is implemented.

[0032] The present invention also proposes a computer, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned phase synchronization method when executing the computer program.

[0033] The phase synchronization method, system, readable storage medium and computer of the present invention analyze the ZCS soft switching operating point of the system under the change of coupling capacitance and provide a stable resonant frequency. When the transmission distance changes, the converter is self-excited by following the zero-crossing point of the resonant current and finally operates at a stable resonant frequency, thereby achieving accurate phase synchronization. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flow chart of a phase synchronization method in a first embodiment of the present invention;

[0035] Figure 2 It is a structural diagram of a bidirectional EC-WPT system of a bilateral LCLC resonance network in a first embodiment of the present invention;

[0036] Figure 3 An equivalent π circuit model diagram of the coupling plate in the first embodiment of the present invention;

[0037] Figure 4 It is a simplified circuit diagram of an equivalent π circuit model of a bidirectional EC-WPT system in the first embodiment of the present invention;

[0038] Figure 5 The waveform diagram of the primary and secondary converter drive signals and the resonant voltage of the bidirectional EC-WPT system in the first embodiment of the present invention;

[0039] Figure 6 The structure and size diagram of the coupling plate in the first embodiment of the present invention;

[0040] Figure 7is a curve diagram of coupling capacitance variation of the coupling plate in the first embodiment of the present invention;

[0041] Figure 8 In the first embodiment of the present invention d =10mm, ZCS soft switching frequency curve of bidirectional EC-WPT system under relative phase angle change;

[0042] Fig. 9 In the first embodiment of the present invention d =15mm, the ZCS soft switching frequency curve of the bidirectional EC-WPT system under the change of relative phase angle;

[0043] Fig.10 In the first embodiment of the present invention d =10mm, the amplitude-frequency and phase curves of the bidirectional EC-WPT system transfer function matrix;

[0044] Fig.11 In the first embodiment of the present invention d =15mm, the amplitude-frequency and phase curves of the bidirectional EC-WPT system transfer function matrix;

[0045] Fig.12 for Figure 1 Detailed flow chart of step S103;

[0046] Fig.13 for Figure 1 A detailed flow chart of another implementation of step S103;

[0047] Fig.14 A block diagram of a phase synchronization method for a bidirectional EC-WPT system of a bilateral LCLC resonant network in a first embodiment of the present invention;

[0048] Fig.15 1 is a circuit schematic diagram of a phase synchronization method in a first embodiment of the present invention, wherein (a) is a primary side, and (b) is a secondary side;

[0049] Fig.16 The resonant current, square wave synchronous voltage drive signal and switch tube drive sequence of the bidirectional EC-WPT system of the bilateral LCLC resonant network in the first embodiment of the present invention, wherein (a) is the primary side and (b) is the secondary side;

[0050] Fig.17 This is a phase synchronization experimental waveform diagram of a bidirectional EC-WPT system of a bilateral LCLC resonant network in the first embodiment of the present invention when the coupling transmission distance is 10 mm;

[0051] Fig.18 This is an experimental waveform diagram of the DC output current of the bidirectional EC-WPT system of the bilateral LCLC resonant network in the first embodiment of the present invention;

[0052] Fig.19 The experimental waveform diagram of the primary and secondary resonant voltages and resonant currents and square wave synchronization signals of the bidirectional EC-WPT system of the bilateral LCLC resonant network in the first embodiment of the present invention, wherein (a) is the primary side and (b) is the secondary side;

[0053] Fig. 20 This is a phase synchronization experimental waveform diagram of a bidirectional EC-WPT system of a bilateral LCLC resonant network in the first embodiment of the present invention when the coupling transmission distance is 15 mm;

[0054] Fig.21 is a structural block diagram of a phase synchronization system in a second embodiment of the present invention;

[0055] Fig. 22 FIG. 4 is a structural block diagram of a computer in a third embodiment of the present invention.

[0056] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0057] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0059] Embodiment 1

[0060] See also Figure 1 , which shows a phase synchronization method in a first embodiment of the present invention, applied to a dual LCLC compensation bidirectional EC-WPT system with a variable coupling capacitance, and the method specifically includes steps S101 to S103:

[0061] S101, initializing the transmission direction of the dual LCLC compensated bidirectional EC-WPT system, and controlling the primary and secondary side converters to perform fixed frequency operation at their corresponding initial operating frequencies respectively;

[0062] In some optional embodiments, before step S101, the method further includes the following steps:

[0063] Acquire a system state vector and a system input vector of the dual LCLC compensated bidirectional EC-WPT system, and construct a state space model of the system according to the system state vector and the system input vector;

[0064] The steady-state operation cycle and the working duration of the dual LCLC compensated bidirectional EC-WPT system are obtained, and the periodic fixed point of the dual LCLC compensated bidirectional EC-WPT system is calculated according to the steady-state operation cycle and the working duration, and the corresponding switch operating point and the corresponding resonant frequency are analyzed based on the steady-state operation cycle and the periodic fixed point.

[0065] In this embodiment, a bidirectional EC-WPT system based on a bilateral LCLC compensation network is shown in FIG2 . Since the bilateral LCLC compensation topology has the advantages of reducing the current and voltage stress of the circuit elements near the coupling plate and the output power is proportional to the coupling coefficient, it is widely used in EC-WPT systems. Figure 2 The electric field coupling mechanism shown includes four metal plates P 1 ~P 4 There is capacitive coupling between every two metal plates, resulting in six coupling capacitors C 12 ~ C 34 , as shown in Figure 3. 1 and P 3 Located on the original side, P 2 and P 4 Located on the secondary side. The coupling capacitor is simplified to an equivalent π model, which is suitable for simplifying the parameter calculation in the circuit. Therefore, Figure 4 shows the simplified circuit diagram of the equivalent π model of the bidirectional EC-WPT system, and the coupling capacitor can be expressed as:

[0066] ;

[0067] in, ;

[0068] According to the KVL law, Figure 4 The differential equation of the equivalent circuit of the bidirectional EC-WPT system of the bilateral LCLC resonant network shown can be expressed as:

[0069] ;

[0070] make x =[ i p u p1 i p2 uin1 u in2 i r2 u r1 i r ] is the system state vector, u =[ u p u r ] T is the system input vector. Then the state space model of the system is:

[0071] ;

[0072] in, A is the system coefficient matrix, B is the system input matrix, which can be obtained as follows:

[0073] ;

[0074] ;

[0075] in

[0076] ;

[0077] According to the on and off states of the primary and secondary converter switches, the system can be linearized into four modes. The resonant voltage and current waveforms are shown in Figure 5 As shown, that is:

[0078] 1. Mode 1: Switches S1, S3, S6 and S8 are turned on, S2, S4, S5 and S7 are turned off, and the system input variable u p = E d , u r =- E o , u 1 =[ E d - E o ] T The steady-state duration is ξ 1 ;

[0079] 2. Mode 2: Switches S1, S3, S5 and S7 are turned on, S2, S4, S6 and S8 are turned off, and the system input variable u p = Ed , u r = E o , u 2 =[ E d E o ] T The steady-state duration is ξ 2 ;

[0080] 3. Mode 3: Switches S1, S3, S6 and S8 are turned off, S2, S4, S5 and S7 are turned on, and the system input variable u p =- E d , u r = E o , u 3 =[- E d E o ] T The steady-state duration is ξ 3 ;

[0081] 4. Mode 4: Switches S1, S3, S5 and S7 are turned off, S2, S4, S6 and S8 are turned on, and the system input variable u p =- E d , u r =- E o , u 4 =[- E d - E o ] T The steady-state duration is ξ 4 .

[0082] Assume that the system steady-state operation cycle is T ξ , the working duration of each linear mode is ξ i ,but

[0083] ;

[0084] Voltage Source uIt can be expressed as:

[0085] ;

[0086] The state mapping function of each mode is:

[0087] ;

[0088] in

[0089] ;

[0090] Assumptions x n is the initial state of the period when the system is in steady state, x n+1 is the end state of the cycle when the system is in steady state, then the system n The stroboscopic mapping model of a working cycle can be expressed as:

[0091] ;

[0092] in, represents the composite mapping operator, defined as .

[0093] In steady state, the state vector of the system repeats periodically, that is:

[0094] ;

[0095] but x n It can be solved as:

[0096] ;

[0097] Since the switch tubes on the same side of the bridge arm of the primary and secondary converters are all 180° complementary conduction, the relationship between the various working modes of the system can be obtained as follows:

[0098] ;

[0099] according to Figure 4 , the relative phase difference between the primary and secondary resonant voltages is defined as θ ,Right now V r = V p ∠ θ ,but θ and ξ 1 The relationship between can be obtained:

[0100] ;

[0101] Therefore, the system period fixed point x * for:

[0102] ;

[0103] If the cycle T As a variable, the periodic fixed point of the system is x * Seen as a cycle T From the fixed point x * By extracting the primary and secondary resonant inductor current components, the system fixed point function used to analyze the ZCS soft switching operating point can be obtained as follows:

[0104] ;

[0105] in, C Select the matrix for the state.

[0106] ;

[0107] make C 1 =[1 0 0 0 0 0 0 0], C 2 =[0 0 0 0 0 0 0 1], from the state vector x The resonant current components are taken out separately i p , i r .

[0108] In order to achieve ZCS soft switching operation, i p , i r The following conditions should be met:

[0109] ;

[0110] Therefore, the ZCS soft switching operating point can be obtained from this formula.

[0111] In addition, according to Figure 4 The system equivalent circuit is shown, and the system transfer function matrix G It can be expressed as follows:

[0112] ;

[0113] in

[0114] ;

[0115] According to the above formula, the amplitude-frequency and phase-frequency relationship curves of each element in the transfer function matrix can be obtained.

[0116] Furthermore, the change of coupling capacitance is analyzed. In practical applications, the position of mobile devices based on the bidirectional EC-WPT system will inevitably shift or the transmission distance will change, causing the coupling capacitance to change randomly. In order to facilitate the analysis, this paper adopts a parallel plate coupling mechanism. The specific structure and size are as follows Figure 6 As shown. Among them, the coupling plate P 1 -P 4 The side length is l =300mm, the thickness of all plates is 2mm, and the transmission distance between the primary and secondary plates is d , P 1 -P 2 and P 3 -P 4 The distance is 150mm.

[0117] The finite element simulation software Maxwell gives the coupling self-capacitance when the coupling plate is laterally offset or the coupling transmission distance changes. C x1 , C x2 and equivalent mutual capacitance C M The change curve of Figure 7 (a) shows the coupling self-capacitance and equivalent mutual capacitance as the transmission distance increases when the coupling plate is not horizontally offset. d A graph of changes; Figure 7 (b) in the figure gives the transmission distance d When the coupling self-capacitance and equivalent mutual capacitance vary with the lateral offset distance of the coupling plate, the coupling self-capacitance and equivalent mutual capacitance are 10 mm. b The simulation results show that: b or d The increasing C x1 , C x2 and C M Keep decreasing. C x1 and C x2 This is because in the symmetrical parallel coupling mechanism, the lateral offset of the coupling plate and the change in transmission distance have the same impact on the two coupling self-capacitances.

[0118] Furthermore, the system resonant frequency is analyzed. Through the above analysis of the change of coupling capacitance, the coupling capacitance will change with the offset of the coupling mechanism or the change of the transmission distance. In order to obtain the multiple soft switching operating points of the system under the change of coupling capacitance, this paper sets the system resonant network parameters to be symmetrical. The system parameters are shown in Table 1.

[0119] Table 1 System parameters

[0120]

[0121] Taking the change of the transmission distance of the metal plate as an example, according to the system circuit parameters and the calculation formula of the resonant current component shown in Table 1, Figure 8 and Fig. 9 They were given d =10mm and 15mm, the multi-soft switch operating point is in the relative phase angle θ The relationship curve under change. Figure 8 It can be seen that the system has a relative phase angle θ When certain changes occur, the ZCS frequency point changes accordingly, and there are 7 ZCS soft switching operating points. At the same time, there are 4 soft switching operating points that remain unchanged with the change of relative phase angle. These 4 inherent resonant frequency points are 0.7062MHz, 0.8078MHz, 1.094MHz and 1.205MHz. Figure 8 Similarly, when the coupling transmission distance d =15mm, the system is in relative phase angle θ Under certain changes, the ZCS soft switch operating points are also 7, such as Fig. 9 As shown in the figure, there are 4 soft switching operating points that remain unchanged as the relative phase angle changes. These 4 natural resonant frequency points are 0.7262MHz, 0.7955MHz, 1.107MHz and 1.183MHz. Figure 8 It can be seen that even when the coupling capacitance changes, the change trend of the system ZCS soft switching operating point is the same, but due to the change of the coupling capacitance, the corresponding ZCS soft switching operating point of the system is changing.

[0122] In addition, since the circuit parameters of the primary and secondary sides of the system are completely symmetrical, Figure 8 and Fig. 9 The given soft switching operating point corresponding to the zero-crossing point of the primary resonant current is completely consistent with the ZCS soft switching operating point corresponding to the zero-crossing point of the secondary resonant current.

[0123] According to the above analysis, it can be seen that under fixed circuit parameters and input conditions, the system has multiple ZCS soft switching operating points. The resonant point of the system refers to the soft switching operating points where the switch drive frequency is consistent with the oscillation frequency, that is, the resonant frequency point of the system is a special soft switching operating point. When the system works in autonomous oscillation mode, the controller controls the switching of the converter in real time according to the zero-crossing signal of the circuit, and finally runs at a stable resonant frequency point. Moreover, the stable resonant frequency point of the system based on autonomous oscillation is related to the output gain of the system, and the oscillation frequency of the system will eventually converge to the point with higher output gain.

[0124] Therefore, according to the transfer function G The calculation formula and the parameters in Table 1 give d =10mm transfer function matrix G The magnitude and phase plots of each element in are as follows: Fig.10 As shown, the maximum gain point of the system is at the resonant frequency of 0.8078MHz. At the same time, Fig.11 Given d =15mm, the amplitude-frequency curve and phase-frequency curve of each element in the transfer function matrix G, the maximum gain point of the system is at the resonant frequency point of 0.7955MHz. Since the system structure and parameters are completely symmetrical, G 11 and G 22 similar, G 12 same G 21 similar.

[0125] S102, after a preset working cycle, performing zero-crossing sampling on the primary converter and the secondary converter to obtain square wave synchronous voltage signals of the primary converter and the secondary converter;

[0126] S103, generating a driving signal of the dual LCLC compensated bidirectional EC-WPT system according to the transmission direction and the square wave synchronous voltage signals of the primary converter and the secondary converter, and self-excitedly driving the converter by following the zero-crossing point of the resonant current, and finally operating at a stable resonant frequency, thereby achieving precise phase synchronization.

[0127] For further information, see Fig.12 , the step S103 specifically includes steps S1031~S1032:

[0128] S1031, when the transmission direction is forward power transmission, defining the primary converter as an inverter, defining the secondary converter as a synchronous rectifier, sampling the resonant current of the primary converter and the secondary converter, and performing a zero-crossing comparison on the sampled resonant current to output a corresponding square wave synchronous voltage signal;

[0129] S1032: Use the square wave synchronous voltage signal to drive the switch tube of the dual LCLC compensated bidirectional EC-WPT system to achieve phase synchronization.

[0130] In some alternative embodiments, see Fig.13 , the step S103 further includes steps S1131-S1132:

[0131] S1131, when the transmission direction is reverse power transmission, defining the secondary converter as an inverter, defining the primary converter as a synchronous rectifier, sampling the resonant current of the primary converter and the secondary converter, and performing a zero-crossing comparison on the sampled resonant current to output a corresponding square wave synchronous voltage signal;

[0132] S1132, using the square wave synchronous voltage signal to drive the switch tube of the dual LCLC compensated bidirectional EC-WPT system to achieve phase synchronization.

[0133] In the specific implementation, through the above analysis, it can be seen that the system will eventually converge to the resonant frequency point with a larger amplitude-frequency gain after autonomous oscillation. Even if the coupling capacitance changes, the system can autonomously oscillate to the corresponding stable resonant frequency point of the system. For the bidirectional EC-WPT system of the bilateral LCLC resonant network, a method such as Fig.14 The phase synchronization method based on the autonomous oscillation mode shown in the figure, the control circuit of the phase synchronization method consists of a current sampling circuit, a zero-crossing comparator and a logic control circuit. The current sampling uses a current transformer to sample the primary and secondary resonant currents, and the sampled current signal is fed to the zero-crossing comparator, which converts the resonant current into a square wave synchronization signal with a duty cycle of 50%. The logic control circuit is divided into two logic signals, one is the driving signal of the system given the initial frequency in the startup phase; the other is the control signal of the system driving the switch tube according to the zero-crossing point of the resonant current.

[0134] The circuit diagram of the phase synchronization method is as follows: Fig.15 As shown, Fig.15 (a) and Fig.15(b) in the figure is a schematic diagram of the sampling circuit of the primary resonant current and the secondary resonant current of the system. During the power-on startup phase, the system drives the primary and secondary switch tubes according to the given initial operating frequency. After the system works at a fixed frequency for a period of time, it starts to oscillate autonomously. At this time, when the controller detects that the resonant current passes through the zero-crossing point of the square wave voltage signal generated by the zero-crossing comparator, the state of the primary and secondary switch tubes changes accordingly, and each branch works at a duty cycle of about 50%. Finally, the output voltage and output current of the primary and secondary converters remain in phase, and the system works at a stable resonant frequency point, achieving phase synchronization of the system.

[0135] The specific steps of the phase synchronization method of the bidirectional EC-WPT system are as follows:

[0136] 1. Transmission direction of system initialization power D , the driving frequency of the primary and secondary converters f p , f r and fixed frequency duty cycle N ;

[0137] 2. The primary and secondary side controllers are respectively based on the initial operating frequency f p , f r Fixed frequency operation N cycles;

[0138] 3. System work N After a period, the sampled primary resonant current i p The square wave voltage signal output by the primary zero-crossing comparator v pz , the sampled secondary resonant current i r The square wave synchronous voltage signal output by the secondary zero comparator v rz ;

[0139] 4. The primary and secondary side controllers are based on the power transmission direction D And the synchronous voltage signal generates the driving signal of the switch tubes S1~S8.

[0140] Specific, definition D =1, the system transmits forward power; D =-1, the system reverses power transmission. The synchronous voltage drive signal and switch tube drive sequence diagram of the system phase synchronization method are shown in Fig.16 As shown. Among them, Fig.16 (a) is the primary resonant current i p , zero-crossing comparator outputs synchronous voltage signalv pz And the driving waveform of the switch tubes S1-S4, Fig.16 (b) is the secondary resonant current i r , zero-crossing comparator outputs synchronous voltage signal v rz And the driving waveform diagram of the switch tubes S5-S8.

[0141] Among them, when D =1, the primary converter is regarded as an inverter and the secondary converter as a synchronous rectifier. When the system performs phase synchronization, it outputs a square wave synchronous voltage signal after sampling the resonant current and then compares it with zero crossing to drive the switch tube. The drive signal of the switch tube S1 and S3 is the same as the square wave synchronous voltage signal of the primary side. v pz In phase, the drive signals of the switch tubes S2 and S4 are v pz Inversion; the drive signal of the switch tubes S6 and S8 is synchronized with the voltage signal output by the secondary zero-crossing comparator v rz In phase, the drive signals of switch tubes S5 and S7 are v rz Invert.

[0142] when D =-1, the secondary converter is regarded as an inverter and the primary converter as a synchronous rectifier. When the system performs phase synchronization, the switch tube is driven according to the square wave synchronization signal output by the sampling current zero crossing comparison. The drive signal of the switch tube S2 and S4 is consistent with the square wave synchronization signal of the primary side. v pz In phase, the drive signals of S1 and S3 are v pz Inversion; the drive signal of S5 and S7 is synchronized with the square wave output of the secondary zero-crossing comparator v rz In phase, S6, S8 drive signals and v rz Invert.

[0143] In order to verify the feasibility of the phase synchronization method based on autonomous oscillation, according to Figure 2 The system circuit shown builds an experimental setup. The system includes a primary and secondary full-bridge converter controlled by two independent controllers. The converter using GaN power modules operates at a switching frequency of MHz.

[0144] The phase synchronization control circuit samples the primary and secondary resonant currents through a current transformer (CU8965-AL), a differential operational amplifier (AD8047) and a high-speed comparator (TL3016), and then generates a square wave synchronous voltage signal for adjusting the primary and secondary drive signals, thereby achieving system phase synchronization and ultimately operating at a stable resonant frequency point.

[0145] The experimental prototype uses the system circuit parameters in Table 1. The primary and secondary parallel compensation capacitors C r1 , C r2 , C p1 and C p2 Use SMD ceramic capacitors. Primary and secondary compensation inductors L r1 , L r2 , L p1 and L p2 Made from Litz wire wrapped around PVC pipe.

[0146] The experimental results of phase synchronization of bidirectional EC-WPT system based on autonomous oscillation are shown below. In order to compare with theoretical modeling and simulation analysis, the phase synchronization based on autonomous oscillation is experimentally verified for two cases where the system transmission distance is 10mm and 15mm respectively. First, the system forward power transmission is set, that is, D =1, the initial fixed frequency operating frequency of the primary and secondary converters f p = f r =1MHz.

[0147] The experimental waveform of phase synchronization when the coupling transmission distance of the system is 10mm is as follows: Fig.17 As shown, the resonant voltage and resonant current of the primary side are v p and i p , the resonant voltage and resonant current of the secondary side are v r and i r . Fig.17 (a) in the figure is a complete transient view of the system switching from fixed-frequency drive to phase synchronization. It can be seen from the figure that the primary and secondary converters are first driven at a given initial frequency. After the system runs at a fixed frequency for a period of time, the primary and secondary converters autonomously follow the synchronous voltage square wave signal after the resonant current zero-crossing comparison, thereby achieving system phase synchronization. The system finally operates at a stable resonant frequency point. Fig.17(c) in Fig.17 The enlarged view of the fixed frequency driving stage in (a) shows that in the initial fixed frequency startup stage, the system drives the primary and secondary converters at an initial frequency of 1MHz. At this time, the primary and secondary resonant currents continue to oscillate periodically. Fig.17 (e) and Fig.17 (f) in is Fig.17 The expanded view of any two moments in (d) in the figure shows more intuitively that the relative phase difference between the primary and secondary resonant voltages of the system keeps changing during the fixed-frequency startup phase. The primary and secondary resonant voltages and currents are out of phase at this time, and the system phase is not synchronized. Fig.17 (d) and Fig.17 (b) in the Fig.17 The enlarged view of the system's autonomous oscillation stage in (a) shows that after the system self-excites and drives the converter following the resonant current zero-crossing point, the primary and secondary resonant currents remain stable, the relative phase difference remains constant, and the resonant voltage and resonant current of the primary (secondary) side are in phase, achieving phase synchronization of the system. At this time, the operating frequency of the system is stable at the resonant frequency point of 0.809MHz, which is consistent with Fig.10 The resonant frequency point of 0.8078MHz at the maximum amplitude-frequency gain of the system shown is highly consistent, proving the consistency of theoretical modeling, simulation analysis and experimental results.

[0148] In addition, the primary and secondary DC output current i d and i o The experimental waveform is as follows Fig.18 As shown in the figure, when the primary and secondary converters operate at a given initial frequency, the primary and secondary DC output currents oscillate continuously and periodically, and the system is in a phase-out state. After that, after the system self-excites and drives the converter following the resonant current zero-crossing point, the DC current of the system remains stable, achieving phase synchronization between the primary and secondary sides of the system and stable operation at the resonant frequency point.

[0149] also, Fig.19 The experimental waveform diagram of the output voltage and current of the primary and secondary converters of the system and the output voltage synchronous square wave signal after the zero-crossing comparator is shown. Fig.19 (a) in the figure gives the primary resonant voltage v p , resonant current i p and synchronous voltage signal v pz , Fig.19 (b) in the figure gives the secondary resonant voltage v r , resonant current i rand synchronous voltage signal v rz It can be clearly seen from the figure that after the primary and secondary resonant currents are sampled and compared with zero crossing, the final output square wave synchronization signal is stable. At the same time, the main reason for the slight difference in phase between the synchronization signal and the resonant current is that the system adds an RC advance compensation network during the resonant current sampling process to compensate for the lag delay of the controller and the drive.

[0150] In order to further verify the feasibility and effectiveness of system phase synchronization when the coupling capacitance changes, d =15mm, the phase synchronization experimental results based on autonomous oscillation are as follows Fig. 20 As shown. Fig.17 and Fig.18 similar, Fig. 20 (a) and Fig. 20 (b) in the figure shows the complete view of the output voltage and output current of the primary and secondary converters and the transient changes of the DC output current before and after phase synchronization. Fig. 20 (c) and Fig. 20 (e) shows an enlarged view of the resonant voltage and resonant current of the system in the initial fixed-frequency driving stage. It can be seen that the system is in a phase-out state at this time. The primary and secondary resonant currents and the DC output current are in continuous periodic oscillation, and the output voltage and current of the primary and secondary converters are out of phase. Fig. 20 (d) and Fig. 20 (f) shows the enlarged view of the resonant voltage and resonant current after the system is phase synchronized. The operating frequency of the primary and secondary sides of the system is stabilized at the resonant frequency of 0.7948MHz, which is consistent with Fig.11 The maximum amplitude frequency gain point shown is consistent. At this time, the primary and secondary resonant currents and DC currents tend to be stable, and the primary and secondary resonant voltages and resonant currents are kept in phase, achieving phase synchronization under the change of system coupling capacitance.

[0151] It can be seen from the above experimental verification and analysis that the phase synchronization method of the bidirectional EC-WPT system based on autonomous oscillation proposed in this embodiment can effectively achieve accurate synchronization of the primary and secondary phases under the condition of coupling capacitance changes.

[0152] In summary, the phase synchronization method in the above embodiment of the present invention analyzes the ZCS soft switching operating point of the system under the change of coupling capacitance and gives a stable resonant frequency. When the transmission distance changes, the converter is self-excited and driven by following the zero-crossing point of the resonant current, and finally works at a stable resonant frequency, thereby achieving accurate phase synchronization.

[0153] Embodiment 2

[0154] Another aspect of the present invention also provides a phase synchronization system, see Fig.21 The phase synchronization system in the second embodiment of the present invention is shown, which is applied to a dual LCLC compensation bidirectional EC-WPT system with coupling capacitance variation. The phase synchronization system includes:

[0155] A data initialization module 11 is used to initialize the transmission direction of the dual LCLC compensated bidirectional EC-WPT system, and respectively control the primary and secondary side converters to perform fixed frequency operation at their corresponding initial operating frequencies;

[0156] A zero-crossing sampling module 12 is used to perform zero-crossing sampling on the primary converter and the secondary converter after a preset working cycle to obtain square wave synchronous voltage signals of the primary converter and the secondary converter;

[0157] The phase synchronization module 13 is used to generate a driving signal for the dual LCLC compensated bidirectional EC-WPT system according to the transmission direction and the square wave synchronous voltage signals of the primary converter and the secondary converter, and to self-excite the converter by following the zero-crossing point of the resonant current, and finally operate at a stable resonant frequency, thereby achieving precise phase synchronization.

[0158] Furthermore, the phase synchronization module 13 includes:

[0159] A forward power transmission unit, used for, when the transmission direction is forward power transmission, defining the primary converter as an inverter and the secondary converter as a synchronous rectifier, sampling the resonant current of the primary converter and the secondary converter, and performing a zero-crossing comparison on the sampled resonant current to output a corresponding square wave synchronous voltage signal;

[0160] The first phase synchronization unit is used to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system using the square wave synchronization voltage signal to achieve phase synchronization.

[0161] In some optional embodiments, the phase synchronization module 13 includes:

[0162] A reverse power transmission unit, used for, when the transmission direction is reverse power transmission, defining the secondary converter as an inverter, defining the primary converter as a synchronous rectifier, sampling the resonant current of the primary converter and the secondary converter, and performing a zero-crossing comparison on the sampled resonant current to output a corresponding square wave synchronous voltage signal;

[0163] The second phase synchronization unit is used to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system using the square wave synchronization voltage signal to achieve phase synchronization.

[0164] In some optional embodiments, the system further comprises:

[0165] A vector acquisition module, used to acquire a system state vector and a system input vector of the dual LCLC compensated bidirectional EC-WPT system, and construct a state space model of the system according to the system state vector and the system input vector;

[0166] A data calculation module is used to obtain the steady-state operation cycle and working duration of the dual LCLC compensated bidirectional EC-WPT system, and calculate the periodic fixed point of the dual LCLC compensated bidirectional EC-WPT system according to the steady-state operation cycle and the working duration, and analyze the corresponding switch operating point and the corresponding resonant frequency based on the steady-state operation cycle and the periodic fixed point.

[0167] The functions or operation steps implemented when the above modules and units are executed are generally the same as those in the above method embodiments, and will not be repeated here.

[0168] The phase synchronization system provided in the embodiment of the present invention has the same implementation principle and technical effects as those of the aforementioned method embodiment. For the sake of brief description, for matters not mentioned in the system embodiment, reference may be made to the corresponding contents in the aforementioned method embodiment.

[0169] Embodiment 3

[0170] The present invention also provides a computer, see Fig. 22 , shown is a computer in the third embodiment of the present invention, including a memory 10, a processor 20, and a computer program 30 stored in the memory 10 and executable on the processor 20, and the processor 20 implements the above-mentioned phase synchronization method when executing the computer program 30.

[0171] The memory 10 includes at least one type of readable storage medium, which includes a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., an SD or DX memory, etc.), a magnetic memory, a magnetic disk, an optical disk, etc. In some embodiments, the memory 10 may be an internal storage unit of a computer, such as a hard disk of the computer. In other embodiments, the memory 10 may also be an external storage device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card, etc. Further, the memory 10 may also include both an internal storage unit of the computer and an external storage device. The memory 10 may be used not only to store application software and various types of data installed in the computer, but also to temporarily store data that has been output or is to be output.

[0172] Among them, in some embodiments, the processor 20 can be an electronic control unit (Electronic Control Unit, abbreviated as ECU, also known as a vehicle computer), a central processing unit (Central Processing Unit, CPU), a controller, a microcontroller, a microprocessor or other data processing chip, used to run the program code stored in the memory 10 or process data, such as executing access restriction programs, etc.

[0173] It should be pointed out that Fig. 22 The structure shown does not constitute a limitation on the computer. In other embodiments, the computer may include fewer or more components than shown in the figure, or combine certain components, or arrange the components differently.

[0174] The embodiment of the present invention further provides a readable storage medium on which a computer program is stored. When the program is executed by a processor, the phase synchronization method as described above is implemented.

[0175] Those skilled in the art will appreciate that the logic and / or steps represented in the flowchart or otherwise described herein, for example, may be considered as an ordered list of executable instructions for implementing logical functions, and may be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For purposes of this specification, "computer-readable medium" may be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0176] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0177] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or a combination thereof: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0178] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0179] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A phase synchronization method, applicable to a dual LCLC compensated bidirectional EC-WPT system with varying coupling capacitance, characterized in that: The method comprises: Initializing the transmission direction of the dual LCLC compensated bidirectional EC-WPT system, and controlling the primary and secondary side converters to perform fixed frequency operation at their corresponding initial operating frequencies respectively; After a preset working cycle, the primary converter and the secondary converter are subjected to zero-crossing sampling to obtain square wave synchronous voltage signals of the primary converter and the secondary converter; The driving signal of the dual LCLC compensated bidirectional EC-WPT system is generated according to the transmission direction and the square wave synchronous voltage signals of the primary converter and the secondary converter, and the converter is self-excited by following the zero-crossing point of the resonant current, and finally operates at a stable resonant frequency, thereby achieving precise phase synchronization, wherein the step of generating the driving signal of the dual LCLC compensated bidirectional EC-WPT system according to the transmission direction and the square wave synchronous voltage signals of the primary converter and the secondary converter includes: When the transmission direction is forward power transmission, the primary converter is defined as an inverter, the secondary converter is defined as a synchronous rectifier, the resonant current of the primary converter and the secondary converter is sampled, and the sampled resonant current is compared for zero crossing to output a corresponding square wave synchronous voltage signal; Using the square wave synchronous voltage signal to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system to achieve phase synchronization; When the transmission direction is reverse power transmission, the secondary converter is defined as an inverter, the primary converter is defined as a synchronous rectifier, the resonant current of the primary converter and the secondary converter is sampled, and the sampled resonant current is compared for zero crossing to output a corresponding square wave synchronous voltage signal; The square wave synchronous voltage signal is used to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system to achieve phase synchronization.

2. The phase synchronization method according to claim 1, characterized in that: Before the step of initializing the transmission direction of the dual LCLC compensated bidirectional EC-WPT system, the method further includes: Acquire a system state vector and a system input vector of the dual LCLC compensated bidirectional EC-WPT system, and construct a state space model of the system according to the system state vector and the system input vector; The steady-state operation cycle and the working duration of the dual LCLC compensated bidirectional EC-WPT system are obtained, and the periodic fixed point of the dual LCLC compensated bidirectional EC-WPT system is calculated according to the steady-state operation cycle and the working duration, and the corresponding switch operating point and the corresponding resonant frequency are analyzed based on the steady-state operation cycle and the periodic fixed point.

3. A phase synchronization system, suitable for a dual LCLC compensation bidirectional EC-WPT system with varying coupling capacitance, characterized in that: The phase synchronization system comprises: A data initialization module, used to initialize the transmission direction of the dual LCLC compensated bidirectional EC-WPT system, and control the primary and secondary side converters to perform fixed frequency operation at their corresponding initial operating frequencies; A zero-crossing sampling module, used for performing zero-crossing sampling on the primary converter and the secondary converter after a preset working cycle, so as to obtain square wave synchronous voltage signals of the primary converter and the secondary converter; A phase synchronization module is used to generate a driving signal of the dual LCLC compensation bidirectional EC-WPT system according to the transmission direction and the square wave synchronization voltage signals of the primary converter and the secondary converter, and self-excite the converter by following the zero-crossing point of the resonant current, and finally operate at a stable resonant frequency, thereby achieving accurate phase synchronization, wherein the phase synchronization module includes: A forward power transmission unit, used for, when the transmission direction is forward power transmission, defining the primary converter as an inverter and the secondary converter as a synchronous rectifier, sampling the resonant current of the primary converter and the secondary converter, and performing a zero-crossing comparison on the sampled resonant current to output a corresponding square wave synchronous voltage signal; A first phase synchronization unit, configured to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system using the square wave synchronization voltage signal to achieve phase synchronization; A reverse power transmission unit, used for, when the transmission direction is reverse power transmission, defining the secondary converter as an inverter, defining the primary converter as a synchronous rectifier, sampling the resonant current of the primary converter and the secondary converter, and performing a zero-crossing comparison on the sampled resonant current to output a corresponding square wave synchronous voltage signal; The second phase synchronization unit is used to drive the switch tube of the dual LCLC compensation bidirectional EC-WPT system using the square wave synchronization voltage signal to achieve phase synchronization.

4. The phase synchronization system according to claim 3, characterized in that: The system further comprises: A vector acquisition module, used to acquire a system state vector and a system input vector of the dual LCLC compensated bidirectional EC-WPT system, and construct a state space model of the system according to the system state vector and the system input vector; A data calculation module is used to obtain the steady-state operation cycle and working duration of the dual LCLC compensated bidirectional EC-WPT system, and calculate the periodic fixed point of the dual LCLC compensated bidirectional EC-WPT system according to the steady-state operation cycle and the working duration, and analyze the corresponding switch operating point and the corresponding resonant frequency based on the steady-state operation cycle and the periodic fixed point.

5. A readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the phase synchronization method as described in any one of claims 1 to 2 is implemented.

6. A computer comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the phase synchronization method according to any one of claims 1 to 2 is implemented.

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