Wireless charging system and control method thereof

Abstract

The present invention discloses a wireless charging system and a control method thereof. The wireless charging system includes a PFC network unit, an inverter network unit, an inverter resonance compensation network unit, a transmitting coil, a receiving coil, a rectifier resonance compensation network unit, a rectifier network unit, a controller, and a WIFI module. The controller adjusts the output power by adjusting the phase difference φ between the inverter network unit voltage VAB and the rectifier network unit voltage Vab, and respectively adjusts the inverter network unit control signal duty cycle D1 and the rectifier network unit control signal duty cycle D2 to control the transmitting coil current to be equal to the receiving coil current, thereby reducing losses. While ensuring the same output power, the present invention minimizes the transmitting coil current and the receiving coil current, thereby reducing coil losses and improving efficiency.

Description

Technical Field

[0001] The present invention relates to a charging device, and in particular to a wireless charging system suitable for charging a car and a control method thereof. Background Art

[0002] With the rapid development of electric vehicles in my country in recent years, achieving safe, convenient, and fast charging for electric vehicles is of paramount importance. The traditional method for charging electric vehicles is to directly draw power from the grid through charging stations. However, when charging electric vehicles with a wired connection, the charging socket or cable often has exposed parts, which can easily generate sparks and arcs during high-power charging, posing a significant safety hazard. Furthermore, traditional wired charging requires manual operation, and human negligence and hardware wear caused by frequent plugging and unplugging of the charging socket can easily lead to poor contact, resulting in personal safety incidents in high-power environments.

[0003] To address these issues, short-range wireless power transmission technology is often used to enable wireless charging of electric vehicles. This technology consists of a PFC network unit, an inverter network unit, an inverter resonant compensation network unit, a transmitting coil, a receiving coil, a rectifier resonant compensation network unit, a controller, and a Wi-Fi module.

[0004] Most existing wireless charging systems control output current by adjusting the duty cycle of the PFC and INV circuits to control the current in the transmitting coil. The current in the receiving coil and rectifier network is determined by the output voltage. High output voltages result in significant losses, affecting overall system efficiency and increasing the cost and size of heat dissipation. Furthermore, output current feedback requires Wi-Fi transmission, which increases control latency, significant hysteresis in the control system, and reduces system stability. Therefore, addressing these issues is crucial for the widespread adoption of wireless charging systems in the electric vehicle sector. Summary of the Invention

[0005] In order to solve the above-mentioned defects in the prior art, the present invention provides a wireless charging system and a control method thereof.

[0006] The technical solution adopted by the present invention is to design a wireless charging system, which includes a PFC network unit, an inverter network unit, an inverter resonance compensation network unit, a transmitting coil BP, a receiving coil VP, a rectifier resonance compensation network unit, a rectifier network unit, a controller, and a WIFI module connected in sequence, wherein the PFC network unit is used to convert AC power into DC power; the inverter network unit is used to invert DC power into high-frequency AC power; the inverter resonance compensation network unit compensates for the leakage inductance of the transmitting coil to improve power transmission efficiency; the transmitting coil converts high-frequency current into AC power. The receiving coil converts the alternating magnetic field into a high-frequency current; the rectifier resonant compensation network unit compensates for the leakage inductance of the receiving coil and improves power transmission efficiency; the rectifier network unit is used to convert high-frequency alternating current into direct current; the WIFI module is responsible for wireless data communication; the controller controls the transmitting coil current to be equal to the receiving coil current by adjusting the phase difference φ between the inverter network unit voltage VAB and the rectifier network unit voltage Vab, and respectively adjusting the inverter network unit control signal duty cycle D1 and the rectifier network unit control signal duty cycle D2, thereby reducing losses.

[0007] The inverter network unit adopts a full-bridge circuit including a first bridge arm and a second bridge arm, and the first midpoint A of the first bridge arm and the second midpoint B of the second bridge arm are connected to the inverter resonant compensation network unit. The inverter resonant compensation network unit includes a first resonant inductor LF1, a first resonant capacitor CF1, and a first capacitor C1, wherein one end of the first resonant inductor LF1 is connected to the first midpoint A, the other end of the first resonant inductor LF1 is connected to the first resonant capacitor CF1 and one end of the first capacitor C1, the other end of the first capacitor C1 is connected to one end of the transmitting coil, and the other end of the first resonant capacitor CF1 is connected to the second midpoint B and the other end of the transmitting coil.

[0008] The rectifier network unit adopts a full-bridge circuit including a third bridge arm and a fourth bridge arm, and the third intermediate point a of the third bridge arm and the fourth intermediate point b of the fourth bridge arm are connected to the rectifier resonant compensation network unit. The rectifier resonant compensation network unit includes a second resonant inductor LF2, a second resonant capacitor CF2, and a second capacitor C2, wherein one end of the second resonant inductor LF2 is connected to the third intermediate point a, the other end of the second resonant inductor LF2 is connected to the second resonant capacitor CF2 and one end of the second capacitor C2, the other end of the second capacitor C2 is connected to one end of the transmitting coil, and the other end of the second resonant capacitor CF2 is connected to the fourth intermediate point b and the other end of the receiving coil.

[0009] The present invention also designs a wireless charging system control method, which adopts the above-mentioned wireless charging system. The control method includes presetting the transmitting coil current IBP or presetting the inverter network unit voltage VAB, adjusting the output power by adjusting the phase difference φ between the inverter network unit voltage VAB and the rectifier network unit voltage Vab, and adjusting the inverter network unit control signal duty cycle D1 and the rectifier network unit control signal duty cycle D2 respectively to control the transmitting coil current to be equal to the receiving coil current, thereby reducing losses.

[0010] In one embodiment, the control method comprises the following specific steps:

[0011] Step 1: Preset the initial value of the transmitting coil current IBP and the initial value of the receiving coil current IVP, and the initial value of the transmitting coil current IBP is equal to the initial value of the receiving coil current IVP;

[0012] Step 2: Calculate the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal according to the initial value of the transmitting coil current IBP and the initial value of the receiving coil current IVP;

[0013] Step 3: Control the inverter network unit voltage VAB and the rectifier network unit voltage Vab to be synchronized, that is, the phase difference φ between the two voltages is 0;

[0014] Step 4: Collect the output voltage Vout and output current Iout of the wireless charging system and calculate the output power Pout;

[0015] Step 5: Subtract the output power Pout from the preset power Pset to calculate the power error Perror;

[0016] Step 6: Calculate the phase difference φ according to the power error Perror;

[0017] Step 7: Determine whether the output power Pout ≥ the preset power Pset and the phase difference φ < 0.5π. If so, go to step 9; otherwise, go to step 8.

[0018] Step 8: The duty cycle D1 of the inverter network unit control signal is increased by the first step length value ΔD1, and the duty cycle D2 of the rectifier network unit control signal is increased by the second step length value ΔD2, and then go to step 4;

[0019] Step 9: Determine whether the phase difference φ is greater than or equal to 0.4π. If so, go to step 11; otherwise, go to step 10.

[0020] Step 10: The duty cycle D1 of the inverter network unit control signal is reduced by the first step length value ΔD1, and the duty cycle D2 of the rectifier network unit control signal is reduced by the second step length value ΔD2, and then go to step 4;

[0021] Step 11: Maintain the current duty cycle D1 of the inverter network unit control signal and the current duty cycle D2 of the rectifier network unit control signal to perform charging, and exit adjustment.

[0022] In step 2, the duty cycle D1 of the inverter network unit control signal is calculated using formula 1, and the duty cycle D2 of the rectifier network unit control signal is calculated using formula 2;

[0023]

[0024]

[0025] Among them, j is the imaginary unit, w o is the resonant angular frequency, L F1 is the inductive reactance of the first resonant inductor LF1, I BP is the initial value of the transmitting coil current IBP, V in is the output voltage of the PFC network unit V in , L F2 is the inductive reactance of the second resonant inductor LF2, I VP is the initial value of the receiving coil current IVP, V out It is the output voltage of the rectifier network unit.

[0026] The step 6 uses formula 3 to calculate the phase difference φ;

[0027] φ(t)=K P *Perror(t)+K I *∫Perror(t)dt Formula 3

[0028] Among them, KP is the proportional coefficient, KI is the integral coefficient, and Perror is the power error Perror.

[0029] In another embodiment, the control method comprises the following specific steps:

[0030] Step 1: Preset the inverter network unit voltage VAB;

[0031] Step 2: collecting the current ILF2 of the second resonant inductor LF2 and calculating the coupling coefficient K according to the rectifier network unit current ILF2;

[0032] Step 3: Calculate the PFC network unit output voltage V according to the coupling coefficient K in and the resonant frequency of the inverter compensation network unit;

[0033] Step 4: Set the transmitting coil current IBP to the maximum transmitting coil current IBPmax, set the receiving coil current IVP to the maximum receiving coil current IVPmax, and calculate the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal respectively;

[0034] Step 5: Control the inverter network unit voltage VAB and the rectifier network unit voltage Vab to be synchronized, that is, the phase difference φ between the two voltages is 0;

[0035] Step 6: Collect the output voltage Vout and output current Iout of the wireless charging system and calculate the output power Pout;

[0036] Step 7: Subtract the output power Pout from the preset power Pset to calculate the power error Perror;

[0037] Step 8: Calculate the phase difference φ according to the power error Perror;

[0038] Step 9: Determine if the output power Pout ≥ Pset*1.1. If yes, go to step 10; otherwise, go to step 11.

[0039] Step 10: Subtract Δn from the emission time of the duty cycle D2 of the rectifier network unit control signal, and then go to step 6;

[0040] Step 11: Determine if the output power Pout is less than or equal to Pset*0.9. If so, go to step 12; otherwise, go to step 13.

[0041] Step 12: Add Δn to the emission time of the duty cycle D2 of the rectifier network unit control signal, and go to step 6;

[0042] Step 13: Maintain the emission moments of the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal, and exit adjustment.

[0043] In step 2, the coupling coefficient K is calculated using formula 4;

[0044]

[0045] Among them, ILF2 is the current ILF2 of the second resonant inductor LF2, wo is the resonant angular frequency, LF1 is the inductive reactance of the first resonant inductor LF1, LF2 is the inductive reactance of the second resonant inductor LF2, VAB is the inverter network unit voltage VAB, LBP is the inductive reactance of the transmitting coil, and LVP is the inductive reactance of the receiving coil.

[0046] In step 3, the output voltage Vin of the PFC network unit is calculated using formula 5, and the resonant frequency of the inverter compensation network unit is calculated using formula 6;

[0047]

[0048] f=85-k*10 Formula 6

[0049] Where V inis the output voltage of the PFC network unit V in , w o is the resonant angular frequency, LF1 is the inductive reactance of the first resonant inductor LF1, LF2 is the inductive reactance of the second resonant inductor LF2, K is the coupling coefficient K, LBP is the inductive reactance of the transmitting coil, LVP is the inductive reactance of the receiving coil, and f is the resonant frequency.

[0050] In step 4, the duty cycle D1 of the inverter network unit control signal is calculated using formula 7, and the duty cycle D2 of the rectifier network unit control signal is calculated using formula 8;

[0051]

[0052]

[0053] Among them, j is the imaginary unit, w o is the resonant angular frequency, L F1 is the inductive reactance of the first resonant inductor LF1, I BP is the maximum transmitting coil current IBPmax, V in is the output voltage of the PFC network unit V in , L F2 is the inductive reactance of the second resonant inductor LF2, I VP is the maximum receiving coil current IVPmax, V out It is the output voltage of the rectifier network unit.

[0054] The step 8 uses formula 3 to calculate the phase difference φ;

[0055] φ(t)=K P *Perror(t)+K I *∫Perror(t)dt Formula 3

[0056] Among them, KP is the proportional coefficient, KI is the integral coefficient, and Perror is the power error Perror.

[0057] The beneficial effects of the technical solution provided by the present invention are:

[0058] During normal operation, the present invention ensures that the transmitting coil current is equal to the receiving coil current. When the output power cannot reach a given value, the transmitting coil current and the receiving coil current are increased simultaneously to ensure uniform current distribution, reduce losses, and improve efficiency. While ensuring the same output power, the transmitting coil current and the receiving coil current are minimized, reducing coil losses and improving efficiency. At the same time, the present invention adjusts power output from startup and can complete power conversion from no-load to full-load without WiFi communication, avoiding the situation where the response speed of traditional wireless charging systems is restricted by WiFi communication speed, thereby improving the robustness of the wireless charging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The present invention is described in detail below with reference to the embodiments and accompanying drawings, in which:

[0060] Figure 1 This is the principle block diagram of the electric vehicle wireless charging system;

[0061] Figure 2 This is the circuit diagram of the electric vehicle wireless charging system;

[0062] Figure 3 This is a waveform comparison diagram of the inverter network unit voltage VAB, the rectifier network unit voltage Vab, and the second resonant inductor LF2 current ILF2;

[0063] Figure 4 It is a rectifier network unit replacement circuit;

[0064] Figure 5 is a control flow chart of the first embodiment;

[0065] Figure 6 This is the control flow chart of the second embodiment. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0067] This patent addresses the shortcomings of existing technologies and proposes a control method that replaces the passive components in the traditional rectifier network with active, controllable components in a conventional wireless charging structure, making the rectifier network and receiving coil controllable. The main advantage lies in increasing the control dimension, ensuring that all resonant network currents are minimized at full output power. Furthermore, by incorporating rectifier network control, loop response speed is no longer limited by Wi-Fi communication time, thereby enhancing the robustness of the wireless charging system.

[0068] The present invention discloses a wireless charging system. Figure 1The principle block diagram of the electric vehicle wireless charging system shown in the figure includes a PFC network unit, an inverter network unit, an inverter resonant compensation network unit, a transmitting coil BP, a receiving coil VP, a rectifier resonant compensation network unit, a rectifier network unit, a controller, and a WIFI module connected in sequence, wherein the PFC network unit is used to convert AC power into DC power (and meet the requirements of indicators such as PF value and THD, and provide a stable DC power supply with a small range of adjustment for the inverter network unit); the inverter network unit is used to invert DC power into high-frequency AC power (in a preferred embodiment, the inverter network unit is composed of a full-bridge MOS / IGBT, and the inverter voltage fundamental effective value is adjusted by adjusting the duty cycle D1); the inverter resonant compensation network unit compensates for the leakage inductance of the transmitting coil to improve the power transmission efficiency; the transmitting coil The receiving coil converts the alternating magnetic field into a high-frequency current; the rectifying resonant compensation network unit compensates for the leakage inductance of the receiving coil and improves power transmission efficiency; the rectifying network unit is used to convert high-frequency alternating current into direct current (in a preferred embodiment, the rectifying network unit is composed of a full-bridge MOS / IGBT or a half-controlled bridge MOS / IGBT, and the effective value of the fundamental wave of the rectified voltage is adjusted by adjusting the duty cycle D2); the WiFi module is responsible for wireless data communication; the controller controls the transmitting coil current to be equal to the receiving coil current by adjusting the phase difference φ between the inverter network unit voltage VAB and the rectifier network unit voltage Vab, and adjusting the inverter network unit control signal duty cycle D1 and the rectifier network unit control signal duty cycle D2, respectively, to reduce losses.

[0069] See Figure 2 In the preferred embodiment shown, the inverter network unit uses a full-bridge circuit including a first bridge arm and a second bridge arm (composed of Q1, Q2, Q3, and Q4). The first midpoint A of the first bridge arm and the second midpoint B of the second bridge arm are connected to the inverter resonant compensation network unit. The inverter resonant compensation network unit includes a first resonant inductor LF1, a first resonant capacitor CF1, and a first capacitor C1. One end of the first resonant inductor LF1 is connected to the first midpoint A, the other end of the first resonant inductor LF1 is connected to the first resonant capacitor CF1 and one end of the first capacitor C1, the other end of the first capacitor C1 is connected to one end of the transmitting coil, and the other end of the first resonant capacitor CF1 is connected to the second midpoint B and the other end of the transmitting coil. In the preferred embodiment, Q1, Q2, Q3, and Q4 use MOS / IGBTs, each with a duty cycle of 0.5. Q1 and Q2 are complementary, and Q3 and Q4 are complementary. The duty cycle of VAB is controlled by controlling the conduction angles of Q1 and Q4. The duty cycle of VAB is represented by D1. Furthermore, according to the impedance relationship,

[0070]

[0071] It can be seen that:

[0072] Where j is the imaginary unit and Wo is the resonant angular frequency, that is, IBP can be controlled by adjusting the duty cycle D1.

[0073] See Figure 2 In the preferred embodiment shown, the rectifier network unit utilizes a full-bridge circuit including a third bridge arm and a fourth bridge arm (composed of Q5, Q6, Q7, and Q8). The third midpoint a of the third bridge arm and the fourth midpoint b of the fourth bridge arm are connected to the rectifier resonant compensation network unit. The rectifier resonant compensation network unit includes a second resonant inductor LF2, a second resonant capacitor CF2, and a second capacitor C2. One end of the second resonant inductor LF2 is connected to the third midpoint a, the other end of the second resonant inductor LF2 is connected to the second resonant capacitor CF2 and one end of the second capacitor C2, the other end of the second capacitor C2 is connected to one end of the transmitting coil, and the other end of the second resonant capacitor CF2 is connected to the fourth midpoint b and the other end of the receiving coil. In the preferred embodiment, Q5, Q6, Q7, and Q8 utilize MOS / IGBTs, each with a duty cycle of 0.5. Q5 and Q6 are complementary, and Q7 and Q8 are complementary. The duty cycle of Vab is controlled by controlling the conduction angles of Q5 and Q8. The duty cycle of Vab is represented by D2. Furthermore, according to the impedance relationship,

[0074]

[0075] It can be seen that:

[0076] Where j is the imaginary unit and Wo is the resonant angular frequency, that is, IVP can be controlled by adjusting the duty cycle D2.

[0077] The main loss in the wireless charging system is caused by the transmitting coil and the receiving coil, which is represented by P = I 2 As we can see from R, losses are proportional to the square of the current. Therefore, if the current IBP of the transmitting coil differs significantly from the current IVP of the receiving coil, this will result in uneven loss distribution and excessive temperature rise. To solve this problem, it is necessary to keep IBP and IVP consistent while maintaining the output power.

[0078] From the relationship between the rectifier resonant compensation network units, we can know that: See Figure 3 The waveform comparison diagram of the inverter network unit voltage VAB, the rectifier network unit voltage Vab, and the second resonant inductor LF2 current ILF2 is shown. The ILF2 current lags behind VAB by 0.5π. By detecting the second resonant inductor LF2 current ILF2, the phase information of VAB can be obtained according to the ILF2 current.

[0079] From the above relationship between the rectifier resonant compensation network units, the output power can be obtained:

[0080]

[0081] The above formula shows that controlling the phase-shift angle φ between Vab and VAB can control the output power. When Vab and VAB are in phase, that is, when the phase-shift angle φ = 0, the ILF2 current is equally positive and negative, resulting in zero output current and power. When Vab leads VAB by 0.5π, that is, when the phase-shift angle φ = -0.5π, the ILF2 current is entirely positive, resulting in maximum output current and power. Based on this principle, by incorporating the control of the rectifier network, the loop response speed is no longer limited by the Wi-Fi communication time, thereby enhancing the robustness of the wireless charging system.

[0082] The present invention ensures that the transmitting coil current is equal to the receiving coil current during normal operation. When the output power cannot reach a given value, the transmitting coil current and the receiving coil current are increased at the same time to ensure uniform current distribution, reduce losses and improve efficiency. The advantage of this patent is that the output power is adjusted by adjusting the phase shift angle φ of Vab and VAB; the output power can be controlled by a single variable to improve the robustness of the wireless charging system. The advantage of this patent is that during normal operation, when working at the rated output power, if the phase shift angle φ of Vab and VAB is too small, it means that the transmitting coil current and the receiving coil current are too large. At this time, the transmitting coil current and the receiving coil current are reduced at the same time to ensure that the transmitting coil current and the receiving coil current are minimized under the same output power, thereby reducing coil losses and improving efficiency.

[0083] Figure 4 The figure shows an alternative circuit for the rectifier network unit. The two upper arms of the rectifier network unit are replaced with conventional diode rectifiers (D1 and D2). The duty cycles of Q6 and Q8 are equal and greater than 0.5, and Q8 lags behind Q6π. By controlling the duty cycles of Q6 and Q8, the duty cycle D2 of Vab is controlled, thereby controlling the receiving coil current IVP.

[0084] See Figure 2 In the preferred embodiment shown, it should be pointed out that the WIFI module is actually divided into a pile / ground-end WIFI unit and a vehicle-end WIFI unit, both of which are responsible for wireless data communication; the controller is actually divided into a pile / ground-end controller and a vehicle-end controller, both of which are responsible for sampling, algorithm implementation, PWM generation, etc.

[0085] The present invention also designs a wireless charging system control method, which adopts the above-mentioned wireless charging system. The control method includes presetting the transmitting coil current IBP or presetting the inverter network unit voltage VAB, adjusting the output power by adjusting the phase difference φ between the inverter network unit voltage VAB and the rectifier network unit voltage Vab, and adjusting the inverter network unit control signal duty cycle D1 and the rectifier network unit control signal duty cycle D2 respectively to control the transmitting coil current to be equal to the receiving coil current, thereby reducing losses.

[0086] exist Figure 5 In the first embodiment shown, the control method includes the following specific steps:

[0087] Step 1: Preset the initial value of the transmitting coil current IBP and the initial value of the receiving coil current IVP, and the initial value of the transmitting coil current IBP is equal to the initial value of the receiving coil current IVP (Note: The initial values are set according to different models and experimental results);

[0088] Step 2: Calculate the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal based on the initial value of the transmitting coil current IBP and the initial value of the receiving coil current IVP (using D1 and D2 to control the operation of the two network units respectively);

[0089] Step 3: Control the inverter network unit voltage VAB and the rectifier network unit voltage Vab to be synchronized, that is, the phase difference φ between the two voltages is 0 (ILF2 current lags VAB by 0.5π, and VAB phase information can be obtained by detecting ILF2 current);

[0090] Step 4: Collect the output voltage Vout and output current Iout of the wireless charging system and calculate the output power Pout (using the common industry formula P=V*I);

[0091] Step 5: Calculate the power error Perror by subtracting the output power Pout from the preset power Pset (the formula is: Perror = Pset - Pou);

[0092] Step 6: Calculate the phase difference φ according to the power error Perror;

[0093] Step 7: Determine whether the output power Pout ≥ the preset power Pset and the phase difference φ < 0.5π. If so, go to step 9; otherwise, go to step 8.

[0094] Step 8: The duty cycle D1 of the inverter network unit control signal is increased by the first step length value ΔD1, and the duty cycle D2 of the rectifier network unit control signal is increased by the second step length value ΔD2, and then go to step 4;

[0095] Step 9: Determine whether the phase difference φ is greater than or equal to 0.4π. If so, go to step 11; otherwise, go to step 10.

[0096] Step 10: The inverter network unit control signal duty cycle D1 is reduced by the first step length value ΔD1, and the rectifier network unit control signal duty cycle D2 is reduced by the second step length value ΔD2, and then go to step 4 (in a preferred embodiment, ΔD1 = ΔD2, and the value range is: between 0 and 0.1);

[0097] Step 11: Maintain the current duty cycle D1 of the inverter network unit control signal and the current duty cycle D2 of the rectifier network unit control signal to perform charging, and exit adjustment.

[0098] In a preferred embodiment, in step 2, the duty cycle D1 of the inverter network unit control signal is calculated using formula 1, and the duty cycle D2 of the rectifier network unit control signal is calculated using formula 2;

[0099]

[0100]

[0101] Among them, j is the imaginary unit, w o is the resonant angular frequency, L F1 is the inductive reactance of the first resonant inductor LF1, I BP is the initial value of the transmitting coil current IBP, V in is the output voltage of the PFC network unit V in , L F2 is the inductive reactance of the second resonant inductor LF2, I VP is the initial value of the receiving coil current IVP, V out It is the output voltage of the rectifier network unit.

[0102] The step 6 uses formula 3 to calculate the phase difference φ;

[0103] φ(t)=K P *Perror(t)+K I *∫Perror(t)dt Formula 3

[0104] Among them, KP is the proportional coefficient, KI is the integral coefficient, and Perror is the power error Perror.

[0105] See Figure 6 In the second embodiment shown, the control method includes the following specific steps:

[0106] Step 1: Preset the inverter network unit voltage VAB;

[0107] Step 2: collecting the current ILF2 of the second resonant inductor LF2 and calculating the coupling coefficient K according to the rectifier network unit current ILF2;

[0108] Step 3: Calculate the PFC network unit output voltage V according to the coupling coefficient K in and the resonant frequency of the inverter compensation network unit;

[0109] Step 4: Set the transmitting coil current IBP to the maximum transmitting coil current IBPmax, set the receiving coil current IVP to the maximum receiving coil current IVPmax, and calculate the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal respectively (in a preferred embodiment, IBPmax=IVPmax, and their values are set according to different models and experimental results);

[0110] Step 5: Control the inverter network unit voltage VAB and the rectifier network unit voltage Vab to be synchronized, that is, the phase difference φ between the two voltages is 0;

[0111] Step 6: Collect the output voltage Vout and output current Iout of the wireless charging system and calculate the output power Pout (using the common industry formula P=V*I);

[0112] Step 7: Calculate the power error Perror by subtracting the output power Pout from the preset power Pset (the formula is: Perror = Pset - Pou);

[0113] Step 8: Calculate the phase difference φ according to the power error Perror;

[0114] Step 9: Determine if the output power Pout ≥ Pset*1.1. If so, go to step 10; otherwise, go to step 11 (it should be noted that Pset is a preset value).

[0115] Step 10: Subtract Δn from the emission time of the duty cycle D2 of the rectifier network unit control signal, and then go to step 6;

[0116] Step 11: Determine if the output power Pout is less than or equal to Pset*0.9. If so, go to step 12; otherwise, go to step 13.

[0117] Step 12: Add Δn to the emission time of the duty cycle D2 of the rectifier network unit control signal, and go to step 6 (the value of Δn is set according to different models and experimental results);

[0118] Step 13: Maintain the emission moments of the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal, and exit adjustment.

[0119] In step 2, the coupling coefficient K is calculated using formula 4;

[0120]

[0121] Among them, ILF2 is the current ILF2 of the second resonant inductor LF2, wo is the resonant angular frequency, LF1 is the inductive reactance of the first resonant inductor LF1, LF2 is the inductive reactance of the second resonant inductor LF2, VAB is the inverter network unit voltage VAB, LBP is the inductive reactance of the transmitting coil, and LVP is the inductive reactance of the receiving coil.

[0122] In step 3, the PFC network unit output voltage V is calculated using formula 5. in , use formula 6 to calculate the resonant frequency of the inverter compensation network unit;

[0123]

[0124] f=85-k*10 Formula 6

[0125] Where V in is the output voltage of the PFC network unit V in , w o is the resonant angular frequency, LF1 is the inductive reactance of the first resonant inductor LF1, LF2 is the inductive reactance of the second resonant inductor LF2, K is the coupling coefficient K, LBP is the inductive reactance of the transmitting coil, LVP is the inductive reactance of the receiving coil, and f is the resonant frequency.

[0126] In step 4, the duty cycle D1 of the inverter network unit control signal is calculated using formula 7, and the duty cycle D2 of the rectifier network unit control signal is calculated using formula 8;

[0127]

[0128]

[0129] Among them, j is the imaginary unit, w o is the resonant angular frequency, L F1 is the inductive reactance of the first resonant inductor LF1, I BP is the maximum transmitting coil current IBPmax, V in is the output voltage of the PFC network unit V in , L F2 is the inductive reactance of the second resonant inductor LF2, I VP is the maximum receiving coil current IVPmax, V out It is the output voltage of the rectifier network unit.

[0130] Step 8 uses formula 3 to calculate the phase difference φ (i.e., the phase shift angle φ between Vab and VAB is obtained after the output power error Perror is calculated by the PI loop);

[0131] φ(t)=K P *Perror(t)+K I *∫Perror(t)dt Formula 3

[0132] Among them, KP is the proportional coefficient, KI is the integral coefficient, and Perror is the power error Perror.

[0133] The advantages of the present invention are that the power output is adjusted from the start, and the power conversion from no-load to full-load can be completed without WiFi communication, thereby avoiding the response speed of the traditional wireless charging system being restricted by the WiFi communication speed; and improving the robustness of the wireless charging system.

[0134] The above embodiments are for illustration only and are not intended to be limiting. Any equivalent modifications or variations made thereto without departing from the spirit and scope of this application should be included in the scope of the claims of this application.

Claims

1. A wireless charging system, characterized in that: It includes a PFC network unit, an inverter network unit, an inverter resonance compensation network unit, a transmitting coil (BP), a receiving coil (VP), a rectifier resonance compensation network unit, a rectifier network unit, a controller, and a WIFI module connected in sequence. The PFC network unit is used to convert alternating current into direct current; The inverter network unit is used to invert direct current into high-frequency alternating current; The inverter resonant compensation network unit compensates for the leakage inductance of the transmitting coil and improves the power transmission efficiency; The transmitting coil converts the high-frequency current into an alternating magnetic field; The receiving coil converts the alternating magnetic field into a high-frequency current; The rectifier resonant compensation network unit compensates for the leakage inductance of the receiving coil and improves the power transmission efficiency; The rectifier network unit is used to convert high-frequency alternating current into direct current; The WIFI module is responsible for wireless data communication; The controller presets the transmitting coil current IBP or the inverter network unit voltage VAB, and controls the transmitting coil current to be equal to the receiving coil current by adjusting the phase difference φ between the inverter network unit voltage VAB and the rectifier network unit voltage Vab, and adjusting the inverter network unit control signal duty cycle D1 and the rectifier network unit control signal duty cycle D2 respectively, thereby reducing losses; The wireless charging system control method includes presetting the transmitting coil current IBP or presetting the inverter network unit voltage VAB, adjusting the output power by adjusting the phase difference φ between the inverter network unit voltage VAB and the rectifier network unit voltage Vab, and adjusting the inverter network unit control signal duty cycle D1 and the rectifier network unit control signal duty cycle D2 respectively to control the transmitting coil current to be equal to the receiving coil current to reduce losses; And includes the following control steps: Step 1: Preset the initial value of the transmitting coil current IBP and the initial value of the receiving coil current IVP, and the initial value of the transmitting coil current IBP is equal to the initial value of the receiving coil current IVP; Step 2: Calculate the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal according to the initial value of the transmitting coil current IBP and the initial value of the receiving coil current IVP; Step 3: Control the inverter network unit voltage VAB and the rectifier network unit voltage Vab to be synchronized, that is, the phase difference φ between the two voltages is 0; Step 4: Collect the output voltage Vout and output current Iout of the wireless charging system and calculate the output power Pout; Step 5: Subtract the output power Pout from the preset power Pset to calculate the power error Perror; Step 6: Calculate the phase difference φ according to the power error Perror; Step 7: Determine whether the output power Pout ≥ the preset power Pset and the phase difference φ < 0.5π. If so, go to step 9; otherwise, go to step 8. Step 8: The duty cycle D1 of the inverter network unit control signal is increased by the first step length value ΔD1, and the duty cycle D2 of the rectifier network unit control signal is increased by the second step length value ΔD2, and then go to step 4; Step 9: Determine whether the phase difference φ ≥ 0.4π, if yes, go to step 11, otherwise go to step 10; Step 10: The duty cycle D1 of the inverter network unit control signal is reduced by the first step length value ΔD1, and the duty cycle D2 of the rectifier network unit control signal is reduced by the second step length value ΔD2, and then go to step 4; Step 11: Maintain the current duty cycle D1 of the inverter network unit control signal and the current duty cycle D2 of the rectifier network unit control signal to perform charging, and exit adjustment.

2. The wireless charging system according to claim 1, wherein: The inverter network unit adopts a full-bridge circuit including a first bridge arm and a second bridge arm, and the first midpoint A of the first bridge arm and the second midpoint B of the second bridge arm are connected to the inverter resonant compensation network unit. The inverter resonant compensation network unit includes a first resonant inductor LF1, a first resonant capacitor CF1, and a first capacitor C1, wherein one end of the first resonant inductor LF1 is connected to the first midpoint A, the other end of the first resonant inductor LF1 is connected to the first resonant capacitor CF1 and one end of the first capacitor C1, the other end of the first capacitor C1 is connected to one end of the transmitting coil, and the other end of the first resonant capacitor CF1 is connected to the second midpoint B and the other end of the transmitting coil.

3. The wireless charging system according to claim 1, wherein: The rectifier network unit adopts a full-bridge circuit including a third bridge arm and a fourth bridge arm, and the third intermediate point a of the third bridge arm and the fourth intermediate point b of the fourth bridge arm are connected to the rectifier resonant compensation network unit. The rectifier resonant compensation network unit includes a second resonant inductor LF2, a second resonant capacitor CF2, and a second capacitor C2, wherein one end of the second resonant inductor LF2 is connected to the third intermediate point a, the other end of the second resonant inductor LF2 is connected to the second resonant capacitor CF2 and one end of the second capacitor C2, the other end of the second capacitor C2 is connected to one end of the transmitting coil, and the other end of the second resonant capacitor CF2 is connected to the fourth intermediate point b and the other end of the receiving coil.

4. A wireless charging system control method, characterized in that: The wireless charging system adopts the wireless charging system according to any one of claims 1 to 3, and the control method includes: in the step 2, the duty cycle D1 of the control signal of the inverter network unit is calculated using formula 1, and the duty cycle D2 of the control signal of the rectifier network unit is calculated using formula 2; Among them, j is the imaginary unit, w o is the resonant angular frequency, L F1 is the inductive reactance of the first resonant inductor LF1, I BP is the initial value of the transmitting coil current IBP, V in is the output voltage of the PFC network unit V in , L F2 is the inductive reactance of the second resonant inductor LF2, I VP is the initial value of the receiving coil current IVP, V out It is the output voltage of the rectifier network unit.

5. The wireless charging system control method according to claim 1, wherein: The step 6 uses formula 3 to calculate the phase difference φ; φ(t)=K P *Perror(t)+K I *∫Perror(t)dt Formula 3 Among them, KP is the proportional coefficient, KI is the integral coefficient, and Perror is the power error Perror.

6. A wireless charging system, characterized in that: It includes a PFC network unit, an inverter network unit, an inverter resonance compensation network unit, a transmitting coil (BP), a receiving coil (VP), a rectifier resonance compensation network unit, a rectifier network unit, a controller, and a WIFI module connected in sequence. The PFC network unit is used to convert alternating current into direct current; The inverter network unit is used to invert direct current into high-frequency alternating current; The inverter resonant compensation network unit compensates for the leakage inductance of the transmitting coil and improves the power transmission efficiency; The transmitting coil converts the high-frequency current into an alternating magnetic field; The receiving coil converts the alternating magnetic field into a high-frequency current; The rectifier resonant compensation network unit compensates for the leakage inductance of the receiving coil and improves the power transmission efficiency; The rectifier network unit is used to convert high-frequency alternating current into direct current; The WIFI module is responsible for wireless data communication; The controller presets the transmitting coil current IBP or the inverter network unit voltage VAB, adjusts the output power by adjusting the phase difference φ between the inverter network unit voltage VAB and the rectifier network unit voltage Vab, and adjusts the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal respectively, controls the transmitting coil current to be equal to the receiving coil current, and reduces losses; And includes the following control steps: Step 1, preset the inverter network unit voltage VAB; Step 2: collecting the current ILF2 of the second resonant inductor LF2 and calculating the coupling coefficient K according to the rectifier network unit current ILF2; Step 3: Calculate the PFC network unit output voltage V according to the coupling coefficient K in and the resonant frequency of the inverter compensation network unit; Step 4: Set the transmitting coil current IBP to the maximum transmitting coil current IBPmax, set the receiving coil current IVP to the maximum receiving coil current IVPmax, and calculate the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal respectively; Step 5: Control the inverter network unit voltage VAB and the rectifier network unit voltage Vab to be synchronized, that is, the phase difference φ between the two voltages is 0; Step 6: Collect the output voltage Vout and output current Iout of the wireless charging system and calculate the output power Pout; Step 7: Subtract the output power Pout from the preset power Pset to calculate the power error Perror; Step 8: Calculate the phase difference φ according to the power error Perror; Step 9: Determine if the output power Pout ≥ Pset*1.

1. If yes, go to step 10; otherwise, go to step 11. Step 10: Subtract Δn from the emission time of the duty cycle D2 of the rectifier network unit control signal, and then go to step 6; Step 11: Determine if the output power Pout is less than or equal to Pset*0.

9. If so, go to step 12; otherwise, go to step 13. Step 12: Add Δn to the emission time of the duty cycle D2 of the rectifier network unit control signal, and go to step 6; Step 13: Maintain the emission moments of the duty cycle D1 of the inverter network unit control signal and the duty cycle D2 of the rectifier network unit control signal, and exit adjustment.

7. The wireless charging system according to claim 6, wherein: The inverter network unit adopts a full-bridge circuit including a first bridge arm and a second bridge arm, and the first midpoint A of the first bridge arm and the second midpoint B of the second bridge arm are connected to the inverter resonant compensation network unit. The inverter resonant compensation network unit includes a first resonant inductor LF1, a first resonant capacitor CF1, and a first capacitor C1, wherein one end of the first resonant inductor LF1 is connected to the first midpoint A, the other end of the first resonant inductor LF1 is connected to the first resonant capacitor CF1 and one end of the first capacitor C1, the other end of the first capacitor C1 is connected to one end of the transmitting coil, and the other end of the first resonant capacitor CF1 is connected to the second midpoint B and the other end of the transmitting coil.

8. The wireless charging system according to claim 6, wherein: The rectifier network unit adopts a full-bridge circuit including a third bridge arm and a fourth bridge arm, and the third intermediate point a of the third bridge arm and the fourth intermediate point b of the fourth bridge arm are connected to the rectifier resonant compensation network unit. The rectifier resonant compensation network unit includes a second resonant inductor LF2, a second resonant capacitor CF2, and a second capacitor C2, wherein one end of the second resonant inductor LF2 is connected to the third intermediate point a, the other end of the second resonant inductor LF2 is connected to the second resonant capacitor CF2 and one end of the second capacitor C2, the other end of the second capacitor C2 is connected to one end of the transmitting coil, and the other end of the second resonant capacitor CF2 is connected to the fourth intermediate point b and the other end of the receiving coil.

9. A wireless charging system control method, characterized in that: The wireless charging system adopts the wireless charging system according to any one of claims 6 to 8, and the control method includes: in the step 2, using formula 4 to calculate the coupling coefficient K; Among them, ILF2 is the current ILF2 of the second resonant inductor LF2, wo is the resonant angular frequency, LF1 is the inductive reactance of the first resonant inductor LF1, LF2 is the inductive reactance of the second resonant inductor LF2, VAB is the inverter network unit voltage VAB, LBP is the inductive reactance of the transmitting coil, and LVP is the inductive reactance of the receiving coil.

10. The wireless charging system control method according to claim 9, wherein: In step 3, the PFC network unit output voltage V is calculated using formula 5. in , use formula 6 to calculate the resonant frequency of the inverter compensation network unit; f=85-k*10 Formula 6 Where V in is the output voltage of the PFC network unit V in , w o is the resonant angular frequency, L F1 is the inductive reactance of the first resonant inductor LF1, L F2 is the inductive reactance of the second resonant inductor LF2, K is the coupling coefficient K, L BP is the inductive reactance of the transmitting coil, L VP is the inductive reactance of the receiving coil, and f is the resonant frequency.

11. The wireless charging system control method according to claim 9, wherein: In step 4, the duty cycle D1 of the inverter network unit control signal is calculated using formula 7, and the duty cycle D2 of the rectifier network unit control signal is calculated using formula 8; Among them, j is the imaginary unit, w o is the resonant angular frequency, L F1 is the inductive reactance of the first resonant inductor LF1, I BP is the maximum transmitting coil current IBPmax, V in is the output voltage Vin of the PFC network unit, L F2 is the inductive reactance of the second resonant inductor LF2, I VP is the maximum receiving coil current IVPmax, V out It is the output voltage of the rectifier network unit.

12. The wireless charging system control method according to claim 9, wherein: The step 8 uses formula 3 to calculate the phase difference φ; φ(t)=K P *Perror(t)+K I *∫Perror(t)dt Formula 3 Among them, KP is the proportional coefficient, KI is the integral coefficient, and Perror is the power error Perror.

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