Phase angle synchronization method for wireless charging system of electric vehicle

Abstract

The invention discloses a phase angle synchronization method for a wireless charging system of an electric vehicle. The phase angle synchronization method realizes phase angle synchronization of rectified input voltage and current of a secondary side of the system. A main circuit of the automobile wireless charging system comprises a direct-current power supply, a high-frequency inverter, a primary side compensation network, a coupling mechanism, a secondary side compensation network, a rectifier, a filter capacitor and a battery load which are electrically connected in sequence, wherein the coupling mechanism comprises a primary side coil and a secondary side coil; the high-frequency inverter adopts a full-bridge inverter circuit, and the rectifier is a half-controlled rectifier bridge adopting a bridge type half-controlled rectifier circuit; the controller is used for controlling the half-controlled rectifier bridge to realize real-time phase angle synchronous control of the electric vehicle wireless charging system based on the SOGI phase-locked loop; wherein the sampling input of the SOGI is iLF2, the feedback quantity of the phase-locked loop is # imgabs0 #, and the output quantity of the phase-locked loop is theta rec; the half-controlled rectifier bridge is a controlled object of the phase-locked loop; the half-controlled rectifier bridge has two input parameters: [theta] rec and [beta] rec.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless charging, and in particular to a phase angle synchronization method for a wireless charging system of an electric vehicle. Background Art

[0002] With the development of new energy technology, electric vehicles are gradually becoming the main force to replace fuel vehicles. With the advantages of low energy consumption, low pollution, energy saving and reliability, electric vehicles will be beneficial to the development and innovation of the electric vehicle industry in the future, making it possible for every household to use electric vehicles for travel.

[0003] Charging electric vehicles through traditional plug-in power supply methods is prone to dangers and troubles such as line aging, leakage fire and equipment failure. With the continuous development of wireless power transmission technology in the field of electric vehicles, due to its advantages of low energy consumption, high efficiency, stability and safety, the use of wireless charging in electric vehicles will become a major trend.

[0004] Wireless charging of electric vehicles generally adopts magnetic coupling resonance. In order to maximize the system transmission power, a DLCC topology magnetic coupling resonant wireless power transmission system is generally used. This topology has the advantages of high transmission power, strong anti-offset capability, strong safety and stability, and the resonant frequency of the system is 85.5kHz.

[0005] For the magnetically coupled resonant wireless power transmission system, both the primary circuit and the secondary circuit are resonant circuits, and the corresponding voltages and currents are in phase. To ensure the synchronization of the primary voltage and current and the secondary voltage and current phases, the switching tube of the secondary rectifier bridge arm and the resonant current flowing through the switching tube can be kept in phase, thereby achieving synchronous rectification and reducing the conduction loss on the switching tube. However, in the actual process, since two sets of controllers are required for the primary and secondary sides of the system, the existing technology cannot ensure the synchronization of the secondary voltage and current phase angles; to ensure the synchronization of the secondary voltage and current phases, it is urgent to build a set of methods for the secondary rectifier bridge of this system that can achieve fast and accurate response of current information in the face of large current harmonics. Summary of the invention

[0006] In view of the above problems, the present invention provides a phase angle synchronization method for an electric vehicle wireless charging system. On the one hand, the input current of the secondary side rectifier bridge is collected, and then the change of the phase difference is tracked by a phase angle synchronization method based on a SOGI phase-locked loop, so as to realize the phase angle synchronization of the rectifier input voltage and current of the secondary side of the system. On the other hand, the collected current signal can achieve the filtering effect after passing through SOGI, which not only saves the cost of adding a filter to the circuit, but also can realize phase angle synchronization more accurately.

[0007] A phase angle synchronization method for an electric vehicle wireless charging system, characterized in that: the main circuit of the automobile wireless charging system includes a DC power supply, a high-frequency inverter, a primary compensation network, a coupling mechanism, a secondary compensation network, a rectifier, a filter capacitor and a battery load which are electrically connected in sequence, and the coupling mechanism includes a primary coil and a secondary coil; the high-frequency inverter adopts a full-bridge inverter circuit, and the rectifier is a half-controlled rectifier bridge adopting a bridge-type half-controlled rectifier circuit;

[0008] The controller is used to control the half-controlled rectifier bridge to realize the real-time phase angle synchronization control of the electric vehicle wireless charging system based on SOGI phase-locked loop;

[0009] The sampling input of SOGI is i LF2 , the feedback quantity of the phase-locked loop is The output of the phase-locked loop is θ rec ;

[0010] The semi-controlled rectifier bridge is the controlled object of the phase-locked loop; the semi-controlled rectifier bridge has two input parameters: θ rec and β rec ;

[0011] Among them, i LF2 is the input current of the half-controlled rectifier bridge; is i LF2 The phase angle of rec is the rectified input voltage u ab The phase angle of rec is the rectified input voltage u ab The phase shift angle.

[0012] It is further characterized by:

[0013] The structure of the SOGI includes a proportional link, a first integral link, and a second integral link connected in series. The input signal is i LF2 , input from the input end of the proportional link, and output signal v after passing through the first integral link α , after the second integration link, the output signal v β , where the sampling current i LF2 With the output signal v α The same amplitude and phase, the output signal v β With the output signal v α Compared with each other, they have the same amplitude and a phase lag of 90°;

[0014] The structure of the phase-locked loop includes a Park conversion unit, a PI controller, an integral link, and a remainder link. The two input ends of the Park conversion unit are respectively connected to the output signal v of the SOGI α With the output signal v β , the phase-locked loop output signal is θ rec;

[0015] The direct-axis component transfer function and the quadrature-axis component transfer function of the SOGI structure are:

[0016]

[0017]

[0018] Where k is the damping factor, ω0 is the undamped natural frequency, and s is the Laplace operator;

[0019] The phase-locked loop output signal θ rec and phase shift angle β rec At the same time, it controls the opening and closing of the half-controlled rectifier bridge switch tubes S5 and S6, thereby controlling the rectifier input voltage u ab The phase and duty cycle of β rec <θ rec <π, S5 is turned off and turned on during the rest of the time. rec >π+β rec When S6 is turned off, it is turned on at other times;

[0020] Preferably, the phase shift angle β rec The control range is [0, π];

[0021] The phase-locked loop output signal θ rec With the sampling signal i LF2 Same phase.

[0022] After adopting the present invention, its beneficial effects are as follows: the primary and secondary power in the wireless charging system of electric vehicles will be affected by the frequency deviation and cause oscillation, so a phase-locked loop is needed to solve this problem, while the use of an open-loop phase-locked loop requires the addition of a filter to filter the sampling signal to improve the phase-locked accuracy, which has the disadvantages of high cost, low phase-locked accuracy, and slow response. The present invention discloses a phase angle synchronization method for an electric vehicle wireless charging system based on a SOGI phase-locked loop. By using a phase tracking technology based on a SOGI (second-order generalized integrator) phase-locked loop, a mathematical model is established, and the phase angle difference between the output voltage and the sampling current is derived and tracked, so that phase angle synchronization can be achieved. Finally, the present invention uses simulation software to build a simulation model to verify that the proposed phase angle synchronization method has excellent feasibility and stability.

[0023] The method of directly measuring the sampling current phase angle saves the cost of additional hardware circuits on the one hand, and on the other hand, due to the filtering effect of SOGI itself, the accuracy and response speed of phase synchronization tracking are improved. Therefore, in view of the problems of high current harmonic distortion rate and low phase detection accuracy in the LCC-LCC topology wireless power transmission system, the present invention proposes a phase angle synchronization method for a car wireless charging system based on a SOGI phase-locked loop, which uses a SOGI phase-locked loop to detect the phase angle of the rectifier bridge input current, obtains its output characteristics through the transfer function of the SOGI structure, and then uses the phase-locked loop to track the phase angle difference change to achieve the phase angle synchronization of the rectifier bridge input voltage and current. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a main circuit schematic diagram of the system corresponding to the present invention;

[0025] Figure 2 Schematic diagram of the main circuit equivalent circuit of the system corresponding to the present invention;

[0026] Figure 3 It is a phase synchronization control block diagram of the present invention;

[0027] Figure 4 A waveform comparison diagram of the SOGI output signal and input signal of the present invention;

[0028] Figure 5 A comparison diagram of the phase-locked loop output waveform and the SOGI input signal waveform of the present invention;

[0029] Figure 6 This is a comparison diagram of the driving waveform of the rectifier bridge switch tube and the output waveform of the phase-locked loop of the present invention;

[0030] Figure 7 The waveform diagram of the input voltage and current of the rectifier bridge of the present invention;

[0031] The names corresponding to the serial numbers in the figure are as follows:

[0032] DC power supply 1, high frequency inverter 2, primary compensation network 3, coupling mechanism 4, secondary compensation network 5, rectifier 6, filter capacitor and battery load 7. DETAILED DESCRIPTION

[0033] A phase angle synchronization method for an electric vehicle wireless charging system, see Figure 1-Figure 7 , when implemented specifically: the automobile wireless charging system is a LCC-LCC topology wireless power transmission system, the main circuit of the LCC-LCC topology wireless power transmission system (see Figure 1) comprises a DC power supply 1, a high-frequency inverter 2, a primary compensation network 3, a coupling mechanism 4, a secondary compensation network 5, a rectifier 6, a filter capacitor and a battery load 7 which are electrically connected in sequence, the coupling mechanism comprises a primary coil and a secondary coil; the high-frequency inverter 2 adopts a full-bridge inverter circuit, and the rectifier 6 is a half-controlled rectifier bridge adopting a bridge-type half-controlled rectifier circuit;

[0034] A DC power supply 1, a high frequency inverter 2, a primary compensation network 3, and a primary coil are combined to form a primary side mechanism; a secondary side coil, a secondary compensation network 5, a rectifier 6, a filter capacitor, and a battery load 7 are combined to form a secondary side mechanism;

[0035] In a specific embodiment, the DC input voltage V DC is 400V, the system drive frequency ω d At 85.5kHz, the compensation inductor L in the primary compensation network f1 The compensation capacitor C is 25μH. f1 is 138.6nF, the compensation capacitor C P is 123.8nF, the transmitting coil L P is 53μH, the receiving coil L S The compensation inductor L in the secondary compensation network is 53μH. f2 The compensation capacitor C is 25μH. f2 is 138.6nF, the compensation capacitor C S It is 123.8nF, where both the transmitting coil and the receiving coil are wound with Litz wire to reduce the resistance value of the coil;

[0036] Figure 2 The schematic diagram of the equivalent circuit of the main circuit of the LCC-LCC topology wireless power transmission system is shown in FIG. In this embodiment, the mutual inductance M between the coils is 14.5 μH, and the filter capacitor C filter 500μF, battery load R L is 20Ω, then the equivalent load R eq About 16.2Ω.

[0037] The controller is used to control the half-controlled rectifier bridge to realize the real-time phase angle synchronization control of the electric vehicle wireless charging system based on the SOGI phase-locked loop;

[0038] refer to Figure 3 The phase synchronization control block diagram shown in the figure, the sampling input of SOGI (second-order generalized integrator) is i LF2 , the feedback quantity of the phase-locked loop is The output of the phase-locked loop is θ rec ;

[0039] The half-controlled rectifier bridge is the controlled object of the phase-locked loop; the half-controlled rectifier bridge has two input parameters: θ rec and βrec ;

[0040] Among them, i LF2 is the input current of the half-controlled rectifier bridge; is i LF2 The phase angle of rec is the rectified input voltage u ab The phase angle of rec is the rectified input voltage u ab The phase shift angle.

[0041] Figure 3 The structure of SOGI includes a proportional link, a first integral link, and a second integral link connected in series. The input signal is i LF2 , input from the input end of the proportional link, and output signal v after passing through the first integral link α , after the second integration link, the output signal v β .

[0042] refer to Figure 4 The SOGI output signal and input signal waveform comparison diagram is shown, where the sampling current i LF2 With the output signal v α The same amplitude and phase, the output signal v β With SOGI output signal v α Compared with each other, they have the same amplitude and a phase lag of 90°;

[0043] Figure 3 The structure of the phase-locked loop includes a Park conversion unit, a PI controller, an integral link, and a remainder link. The two input ends of the Park conversion unit are connected to the SOGI output signal v α With SOGI output signal v β ;

[0044] The direct-axis component transfer function and quadrature-axis component transfer function of the SOGI structure are:

[0045]

[0046]

[0047] Among them, the damping factor k is 1.414, the undamped natural frequency ω0 is 2*π*85500, and s is the Laplace operator;

[0048] refer to Figure 5 The phase-locked loop output waveform is compared with the SOGI input signal waveform. The phase-locked loop output signal is θ rec ; Phase-locked loop output signal θ rec With the sampling signal i LF2In this embodiment, the output range of the phase-locked loop output signal is [0, 2π], the phase shift angle β rec The control value is 0.5π;

[0049] refer to Figure 6 The rectifier bridge switch tube driving waveform shown in the figure, the phase-locked loop output signal θ rec and phase shift angle β rec At the same time, it controls the opening and closing of the half-controlled rectifier bridge switch tubes S5 and S6. In each time period [0, 2π], when 0.5π<θ rec <π, S5 is turned off and turned on during the rest of the time. rec >1.5π, S6 is turned off and turned on at other times; thus controlling the rectifier input voltage u ab The phase and duty cycle;

[0050] The output rectifier bridge voltage waveform reference Figure 7 shown.

[0051] In this embodiment, the phase of the voltage signal output by the phase lock is almost consistent with the phase of the collected current signal, thereby achieving phase angle synchronization of the input voltage and current of the secondary rectifier bridge.

[0052] The beneficial effects are as follows: the primary and secondary power in the electric vehicle wireless charging system will be affected by the frequency deviation and cause oscillation, so a phase-locked loop is needed to solve this problem, while the open-loop phase-locked loop needs to add a filter to filter the sampling signal to improve the phase-locked accuracy, which has the disadvantages of high cost, low phase-locked accuracy, slow response, etc. The present invention discloses a phase angle synchronization method for an electric vehicle wireless charging system based on a SOGI phase-locked loop. By using the phase tracking technology based on a SOGI (second-order generalized integrator) phase-locked loop, a mathematical model is established, and the phase angle difference between the output voltage and the sampling current is derived and tracked, so that phase angle synchronization can be achieved. Finally, the present invention uses simulation software to build a simulation model to verify that the proposed phase angle synchronization method has excellent feasibility and stability.

[0053] The method of directly measuring the sampling current phase angle saves the cost of additional hardware circuits on the one hand, and on the other hand, due to the filtering effect of SOGI itself, the accuracy and response speed of phase synchronization tracking are improved. Therefore, in view of the problems of high current harmonic distortion rate and low phase detection accuracy in the LCC-LCC topology wireless power transmission system, the present invention proposes a phase angle synchronization method for a car wireless charging system based on a SOGI phase-locked loop, which uses a SOGI phase-locked loop to detect the phase angle of the rectifier bridge input current, obtains its output characteristics through the transfer function of the SOGI structure, and then uses the phase-locked loop to track the phase angle difference change to achieve the phase angle synchronization of the rectifier bridge input voltage and current.

[0054] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0055] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A phase angle synchronization method for an electric vehicle wireless charging system, characterized in that: The main circuit of the automobile wireless charging system includes a DC power supply, a high-frequency inverter, a primary compensation network, a coupling mechanism, a secondary compensation network, a rectifier, a filter capacitor and a battery load which are electrically connected in sequence, and the coupling mechanism includes a primary coil and a secondary coil; the high-frequency inverter adopts a full-bridge inverter circuit, and the rectifier is a half-controlled rectifier bridge adopting a bridge-type half-controlled rectifier circuit; The controller is used to control the half-controlled rectifier bridge to realize the real-time phase angle synchronization control of the electric vehicle wireless charging system based on SOGI phase-locked loop; The sampling input of SOGI is i LF2 , the feedback quantity of the phase-locked loop is The output of the phase-locked loop is θ rec ; The semi-controlled rectifier bridge is the controlled object of the phase-locked loop; the semi-controlled rectifier bridge has two input parameters: θ rec and β rec ; Among them, i LF2 is the input current of the half-controlled rectifier bridge; is i LF2 The phase angle of rec is the rectified input voltage u ab The phase angle of rec is the rectified input voltage u ab The phase shift angle.

2. A phase angle synchronization method for an electric vehicle wireless charging system according to claim 1, characterized in that: The structure of the SOGI includes a proportional link, a first integral link, and a second integral link connected in series. The input signal is i LF2 , input from the input end of the proportional link, and output signal v after passing through the first integral link α , after the second integration link, the output signal v β , where the sampling current i LF2 With the output signal v α The same amplitude and phase, the output signal v β With the output signal v α Compared with the same amplitude, the phase lag is 90°.

3. A phase angle synchronization method for an electric vehicle wireless charging system according to claim 2, characterized in that: The structure of the phase-locked loop includes a Park conversion unit, a PI controller, an integral link, and a remainder link. The two input ends of the Park conversion unit are respectively connected to the output signal v of the SOGI α With the output signal v β , the phase-locked loop output signal is θ rec .

4. The phase angle synchronization method of the electric vehicle wireless charging system according to claim 3, characterized in that: The direct-axis component transfer function and the quadrature-axis component transfer function of the SOGI structure are: Where k is the damping factor, ω0 is the undamped natural frequency, and s is the Laplace operator.

5. The phase angle synchronization method of the electric vehicle wireless charging system according to claim 4, characterized in that: The phase-locked loop output signal θ rec and phase shift angle β rec At the same time, it controls the opening and closing of the half-controlled rectifier bridge switch tubes S5 and S6, thereby controlling the rectifier input voltage u ab The phase and duty cycle of β rec <θ rec <π, S5 is turned off and turned on during the rest of the time. rec >π+β rec S6 is turned off when the power is on, and is turned on at other times.

6. A phase angle synchronization method for an electric vehicle wireless charging system according to claim 5, characterized in that: The phase shift angle β rec The control range is [0, π].

7. The phase angle synchronization method of the electric vehicle wireless charging system according to claim 3, characterized in that: The phase-locked loop output signal θ rec With the sampling signal i LF2 Same phase.

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